These Boer Wars guerillas...
...seem like they could be modeled with some "wild west" style figures - some generic "cowboys" could find a lot of use outside of North America, and this is a great example!
They don't seem to be an exception to the rule, either - I see lots of similar pictures turn up in image searches:
Wargames Atlantic has a Sepoy Rebellion (1857) British set listed in the release schedule, in final parts check - I don't think these have been previewed or teased yet, but I'm going to go out on a limb and say they might be pretty close to the uniforms and equipment of the British in the Boer Wars (1880-1890s), with maybe a little fudging and hand-waving.
That might leave any proper Boer (army? militia?) uniforms - not sure what those even look like, the image search results mostly looks like the sort of ragtag militia above, the rest don't seem very consistent, sometimes in longer jackets with wide-brimmed soft hats, sometimes in shirt-sleeves and suspenders with pith helmets, etc. - I'm guessing there were a mix of local militias who sometimes had their own uniforms, and often didn't, but it's hard for me to tell at a glance!
Seems like a fascinating subject for wargaming to me.
I'm always in favor of VSF bits where practical, either included in the kit, or provided separately via Death Fields Accessory Sprues - the "cowboy" types seem like a fun subject for VSF/Weird West/Steampunk sorts of modeling and gaming, the upcoming Deathfields "Bulldogs" seems to have the subject covered for the British, leaving any uniformed Boers up in the air - anything that can be done to give the Boers extra utility is great, though.
So, in short - seems like an interesting wargaming subject; I'm guessing the upcoming Sepoy British sets will be 'close enough' for the British, while the Boers seem to be a mix of uniformed and non-uniformed militias, to my untrained eye, and I think that a Wargames Atlantic Wild West/Cowboy set would cover a lot of Boer territory, depending on what WGA does with it - with or without sci-fi bits, I'd be interested in a good Wild West set, and any sci-fi/fantasy bits would only be icing on that cake! A "cowgirl" set would be a blast and might cover a lot of Victorian era female "partisan" type situations, but I don't know how niche it would be. The Death Fields "Bulldogs" seem to have the sci-fi British covered.
A proper uniformed Boer set seems like an obvious place to start, in any event!