Will 10yo's actually value separate channels? Or will OP's daughter just end up being the "other weird kid on the weird app we dont like". I know nothing about 10yo's though, maybe I am wrong.

isn't sms better than being forced instagram dm or smth tho..?

Yeah, that's exactly my point. I am not a parent, but in my opinion, it would be better to allow the use of whatever platform is the default, maybe provide an alternative, and give the child an age appropriate understanding of what using Instagram/Whatever means to them. "You can use it, but don't say anything private like our address, because your private messages can be read by the company. If you need to say something private, use signal/matrix/whatever else, because that's safe.". Maybe if your lucky they can pass that knowledge to their friends as well.

Kids are walking privacy violations at the best of times anyway, education needs to start early.