This. I can’t even get most people to switch from WhatsApp to Signal. Because everyone is already on WhatsApp so it just works for them.

While that is true, there have been many discussions about if there are any known security vulnerabilities or new spec changes that would cause a problem. The consensus from the community is that it is safe to use for quite some time. Not invalidating your points in any way just putting out what I know.

Personally I would use andOTP on my mobile with backups and use OTPClient on my computer. I don’t like having my 2 factor auth stored in the same system as my passwords. Because if the password manager was ever lost or stolen you’d have all your eggs in one basket essentially.