Surprisingly, the standalone apk version is able to self-update and will remind you to do so.

If they put it on f-droid they'd automatically get auto updates as well.

Well yes, but also because their app is proproetary. As in, it bundles proprietary dependencies, in particular for google push system and there was a proprietary dependency for audio processing, too.

More things can be said, e.g. that Molly actually "fixes" these problems... But I think it's fair to mention what I wrote above.