Instances can be created freely, and are free to both associate and disassociate with other instances as they please.

Each instance decides their comfort with content within their instance and outside it. There are left leaning instances, centrist ones, and I’m sure a few right leaning ones. Some are ban-happy, but many will allow you to post all sorts of content, as long as it’s not too outlandish.

If the content you wish to see/post is wildly outside the overton window, you can join an instance that allows this or create your own. But other instances are under no obligation to federate with content they don’t wish to see.

Stuff like PostmarketOS looks interesting. The new Furilabs phone doesn’t sound too bad either.

If you have the money, consider donating $5 to a couple Linux mobile projects. Small donations here and there can be the difference needed to make Linux mobile a viable option.