do you think trolls would have blood color variations depending on the troll? like, if you looked at the blood of two rust-bloods, would one be slightly more saturated and the other one slightly darker?

So far that doesn’t seem to be the case, but there’s nothing preventing that from being the case to be honest. Additionally, even with the same Blood Colors, some Trolls type in shades different to their Blood tone, so there’s that too.