[Aachen]

Yes, Microsoft tries to get you to use their proprietary mechanism by default. You need to click on the "use a different method" link when doing the setup to get a code that is compatible with e.g. Google Authenticator, FreeOTP, and all the other ones

[riedel]

The last time I tried to that for an external MS Teams instance, the option to use another method was gone. Could have been a compliance thing of the 'owner' of the instance, however, I actually tried multiple times to circumvent installing their app, but failed.

[unethical_ban]

It's a setting of the app owner. I ran into the same thing. Though I admit a push based 2FA is more resistant to phishing.