Some tips to fight big tech platforms while still using them for movement building and information spreading:
Use a vpn every time you are online.
If u have an Android u can make a work profile (it's a kind of sandbox that isolates apps on your phone).
Don't use it for entertainment and doom scrolling but just open the pages u want to read info from (use it like a newspaper).
It's really ok to be full of contradictions but there are some anti surveillance/ ethical measures that u can take.
Mastodon is still small, not as international and intergenerational as the other big platforms. But from an ethical perspective it seems like the best choice today.
But, from a political/propagandist standpoint the argument for using Instagram is there. Although we over estimate our power in the spreading of information on those platforms. If your software is not open source the algorithms will win.
Also don't underestimate how quickly people can adapt to different platforms. But, if you can only contact your grandma through WhatsApp that's totally fine.