[Loranubi]

Because I got fed up with all the existing 2FA apps (lack of backup, export, ...) I created a simple (desktop) CLI app which works for me: https://github.com/Dobatymo/otp-tool

It's just a one day project so far. But it has some nice features like taking a screenshot and reading qr codes from it and storing everything in a single enrypted file (which you can easily put on a cloud drive if you want to sync, otherwise it's completely offline)

It only supports the standard RFC 6238 TOTP so far.

[UberFly]

Nice role-your-own solution. Just a FYI - Aegis does have backup, export etc. I would also not use it if it couldn't export.