You have a FIDO key, set it up the same as any other 2FA. You plug it in, set up a PIN. When you get challenged to enter your 2FA, instead of getting an SMS, you just plug the key in a USB port and enter your pin, then touch the key, job done. Mine are the Security Key NFC I think...although both USB-A....I need to get a USB-C one really now I'm almost fully migrated to USB-C.
I've two keys, one on my keyring, once stored at home. Those are used to secure my email accounts and password manager (Proton Pass). Also a printout of recovery codes stashed somewhere as a last resort.
I wouldn't trust any mobile company on principle. If you use SMS/Phone 2FA you are effectively just handing the keys to your accounts to your mobile provider and trusting them.
Use authenticator apps, printed codes, FIDO keys.....and only then are YOU in control of your accounts.