As tootle is the only mastodon client directly available in PureOS (heck, why?), I gave it a try with my brandnew librem.one account.
I actually could use it about half an hour, but then continued directly in the browser (tootle isn't really... a revelation).
Next day, I reopened the app, and it immediately crashed, reproducibly.
I assume the new content in my account somehow provoked it.
[ERROR 23:04:11.122900] [GLib-GIO] Settings schema 'io.elementary.desktop.wingpanel.datetime' is not installed
Personally, I don't care too much about it, but crashes never look good, and possibly it's a simple fix.