Personally I think they need to do more non-human options that are not "Classic fantasy races in space" after the Damned get done in plastic and this idea is not out of line with accomplishing that.
Maybe instead of just a mystery science team, make them an alien exploratory force/science corp/science expedition, with the backstory that they are an "unbacked team" that is actually in the circuit by accident because they are lost: Thier navigational computer is dead, they don't speak any of the known "true civilization" languages so they can't ask for directions, and they have a horrible sense of direction that is equal to Ryoga Hibiki’s epic inability to get from point A to point B😆. Yeah, really lost in space🤣.
Of course the original "humie science team" idea you had could honestly be done as a non-Death Fields set and the start of a new SciFi line more believably lore wise, which would not be a bad idea. Frankly Death Fields is more "Battle tournaments in space" than good adventure SciFi which is a pretty big niche now thanks to starfinder and Stargrave (not to mention all the other SciFi TTRPGs), plus if done in WA's non Death Field normal "historical scale" it would work great with the Iron Core sets and other historical scale sets for time travel nonsense and probably get more of the parts you want on the sprue with less sacrifice to the number of bodies (less chunky proportions equals more stuff on the sprue).
It doesn't seem like the kind of thing that will sell in large numbers, which a hard plastic kit needs to do. Definitely a more niche product, better suited to 3d prints or potentially metal. Off of the top of my head I can think of a few things that are already close-ish to what you describe, and the Cannon Fodder could make for a reasonable approximation, barring some of the more fanciful weapons you describe.
https://bombshellminis.com/gcw/
https://www.battleprints.co.uk/products/space-dwarf-exo-dwarves-x-3-federation-of-tyr
https://mustcontainminis.com/2021/03/american-power-armour-by-gaddis-gaming.html
aside from the retro-scifi weapons, you could get fairly close by putting cannonfodder spacesuit heads onto the Eisenkern armors.
I wonder if this could be made to work commercially with a stronger visual identity. Fallout Wasteland Warfare seems to sell, so there seems to be a market for that kind of 1950's American retro-futurist aesthetic with hints of pulp sci-fi thrown-in. You mention diving suits, which reminds me of the Big Daddies from Bioshock, although they were typically armed with industrial equipment, like large drills or rivet-guns, be visually were of that same era.
I think this could become something that could reasonably stand-in for something like Mantic's Veer Myn (drills and rayguns) or some kind of wierd-war/alternative history pulp-scifi, but I'm still dubious about the breadth of such a kit's appeal. It also doesn't fit into the DF theme of historical armies transported to a sci-fi setting. Generally the DF kits work as historical or moderns in heroic 28mm scale if you leave out the overtly sci-fi weapons.
Alternatively, this could make good fodder for another weapon/upgrade sprue. I don't know how well the previous one sold, but if another is on the cards then perhaps pulp sci-fi weapons and heads that could be thrown at a variety of other kits would work well enough to get into production, and allow you to create the army you describe with bodies from elsewhere?
What Death Fields really needs is a Scavenger set. Somthing that leans heavily on the gasmask, cloaks, and robes vibe (and can take on Frostgrave's Cultist box). Skirmish gamers have no issues getting their hands on autoguns and lasguns. What is needed is a scavengers set that dives hard into muskets, crossbows, blunderbuss, and jezzails. The kind of primitive weaponry that Mad Max should have devolved into but somehow abandoned the hard realism of 80's Road Warrior. Give me weaponry (and scrap armor, please make it scrap bits you can attach, not full torsos and legs) that could be manufactured by outlaws, outlanders, and ashwaste nomads from Necromunda.
If you give us cloaked and hooded scavengers, you give us nomads, cultists, sand folk, outlaws, refugees, space pirates, fremen, scavvies, skaven, and so much more. If you keep the weaponry primitive, scrap manufactured, survivialist; folks will buy the kit just to arm any wastlander crew starting at the bottom. And if the weapons are basic enough they can be used interchangably in fantasy and sci-fi games. All I'm saying is don't empasize the AK-47s, we all have enough of those in our bit box.
Give me bits to attach to a Space Orc Spawning, where an orc emerges from filth and a goblin hands him a sack of javelins made from scrap and a cracked blunderbuss. Those jezzails from the lizard man box are great, but only so many scavvies can have reptile claws...
A good scavengers set doesn't just let me make one crew, it helps me build several. And its worth buying again. I'm already on my second box each of Frostgrave cultists and wizards... and I dont even play Frostgrave.
@INSURGENT Skirmisher Again wait for the Damned sets they have a bit of that going for them though honesstly the original concept STLs had more of that but most folks apparently don't like the scrap look argueing its better to have uniformity in plastic and then just modify it (litterally argued tooth nail with those hammerheads everytime this was brought up in the crowdfund just to keep the damned scarppy looking and not Cadians with gasmasks).
In the meantime buy WFB fantasy bits to mix in.
@INSURGENT Skirmisher I'm interested to hear what kind of games you would want these for? The only post apocalyptic rulesets I'm aware of are Fallout (Warfare and Wasteland Warfare) and a variant of Xenos Rampant. (Necromunda perhaps?)
Also, I can think of a few model kits available now that are similar, but not quite what you're describing: Northstar just recently launched a scavenger kit for Stargrave, Pig Iron's Colony Ferals have some real post-apocalyptic vibes, Spiral Arm's Broken Infantry have a very scrappy aesthetic and GW's Cawdor gang have several weapons along the lines you've described. How well do you feel those and similar kits work for what you want to build?
@Stephen Sutton there are quite a few Post Apoc games actually (some are quite old now) and post apocalyptic rule sets can generally be classed in two main "historical timeline" categories:
Its either:
Farish future with truelly out there space age tech like energy weapons and anti grave tanks like "Mutants and Death Rays"is which generally coast on Mad Max/Fallout vibs though some are truely thier own thing, either way you can pretty much use 40k figures and models for most of these games.
Or its:
Closer to now alternet modern settings games with real guns, gear, and vehicles like zona alfa or Project Z which are honestly an excuse to play with the Modern "armed civilian" and "Zombies" figures folks keep making.