For standard RFC6238 TOTP you can just use this:

https://github.com/rsc/2fa/

    oathtool --base32 --totp "SECRET2429190" | pbcopy # servicename

servicename as added comment for convienient reverse search.

checkout Ente Auth! It's a native desktop app, syncs with the mobile app, and is fully open source. Great company as well, also free (as in beer).

https://ente.com/auth/