As my avatar suggests, I support the idea of using Free Software, online and off.
Comfort with the tools matters, too. If a person sees the transition from, say, Twitter or FB to Mastodon as a relatively painless one, great.
If they resist the change becuuse it is too "different", then you'll only attract the flexible ones. (Anarchists?)
I've switched my focus, but my peripheral vision is still working.
I'm most comfortable here (for the time being), but I keep my accounts elsewhere.
As for "dispositive tools", I am going to read up on that one. I am not a lawyer, nor do I play one on TV.
It sounds like you feel you cannot be yourself in an important way because of the choice of online tool. Is that an accurate read?
If you decided to re-center your online activities with reliance on Free tools, will it also matter who is operating the servers involved?
If you have the skills, it sounds like you would do well to consider setting up a server or more from which you can federate.