>data isn't restricted to what you have on your computer/dumbphone
No, but it is restricted by what information I provide them with, they can't for example, be tracking the links to external sites I visit from my client while Twitter can (because they have that stupid t.co shortener service). In fact maybe I could get Twidere to support Tor so they don't even get my real IP.
>your posts, IP,
You mean like literally every site on the internet because they need that information to function anyway, including 8chan. There will always be some obscure debug log somewhere of a certain IP requesting data from them, even if a site claims they 'aren't logging'.
>are still being shared/sold
>mouse movements, how fast you type, time spent reading
They can't monitor that site, like I said, third party client, even if Mastodon was recording this stuff (idk, but it's libre so you can audit the source code if you want).