Plus open software on phones and tablets is still in very early stages.

This simply isn't true. However your first comment about OS level checks is where the issue lies - if you don't phone home to Google your banking app won't work.

On a PC that isn’t so hard to do. The problem though is that online services will start requiring the os level check

Easy peasy, the browser checks the OS them reports it to the website

Linux is the giant it is using email as the primary infrastructure for development. We will be fine.

Can't we just fork it over to something like Codeberg eventually? I know it's a lot to move over, but with time and patience, it seems achievable.