One that's actually "based" but isn't some whiny retard? They don't exist. At best you get content creators that are obviously left leaning at a minimum but leave the politics out of it, but that's mostly on the painting side of things. Not lore or gameplay. They're either whiny morons who haven't played in years and bitch about everything GW does like it's the end of the fucking world, or they're just right wing grifters instead of woke morons from the left.
Kroot have a detachment in the codex(kroot hunting pack), and there's also a joint species detachment that Tau just got the other week(auxiliary cadre) that does shit like force opponents to re-target kroot instead of shooting at Tau assets(among other things).
Really the biggest problem kroot have is that for the most part, they're Tau chaff units so running an army of them is never going to be great due to them not having much(like wanting to run an all grot ork army, or an all cultist chaos army, shit like that) in addition to being t3 6+(but it makes sense due to most of them having scout, infiltrator, stealth, etc.), or a whopping t6 5+ for the mounted units. Vespid are at least t4 4+. Tau auxiliary races really are just a "fluff" thing for GW for a while now, but at least the new detachment tries to cater to people who want that.
If you want to see a real dumpster fire of a mixed up army that doesn't need to exist, Imperial Agents does it far worse than Tau. However GW wanted an excuse to sell a codex for a bunch of units imperial players were taking as allies.
