We have a two-man rule for such accounts: one person (or one group) is responsible for the password, and the other has the 2FA secret on their Yubikey. The other rule is to not use these accounts; as an example use use root AWS accounts once or twice a year when we need to fill in their forms.
How about just do it?
Ever shared a USB key or a company phone. There isn't much to describe.
I guess if all the people who need access are in the same physical location that works.
By sticking the same base code into Google Authenticator or similar?
I didn't think that was possible at least with Google accounts. But now that I think about it, if you set up both devices from the same QR code (instead of running through the process twice) it should work. Good idea.