Thanks for sharing. Syncing data across devices is heavily overrated in my view and often just creates unnecessary vulnerabilities. I have an authenticator app on my phone and back up the secrets manually to an offline location whenever I add a new account. It's not that much of an inconvenience and I like the extra control and assurance that the app isn't phoning home anywhere.
Discussion
💯 I too use Ravio and export the 2FA secrets in an encrypted zip file using the app itself. I have setup an automated script to back it up occasionally with shortcuts to my backup drives.