The issue was me not having a screen lock passcode defined.

Not sure if this is the best way to approach this, a settings page for editing user information (including name and root password) would be useful, that one could then opt out for the screenlock.

I'm using Firefox on Ubuntu Touch (focal), but I've found that I can't copy anything to native apps.

I don't know if it this is limited to Firefox, or if it still happens with a physical keyboard, but it seems to me that the clipboard isn't being shared with the native/host OS. Is this intended behavior and is there a way to workaround it?