[latchkey]

While I'm sure that Fi and Google Voice are better than almost any other carrier based SMS security, this does nothing to convince me to ever use SMS 2FA.

"Your Fi number is tied to your Google Account." -- I'm sure you've seen cases of people's google accounts being randomly locked for no reason. Now you lose access to make a call too!

The last thing I'd ever trust security to is SMS. Lots of good technical details here:

https://lucky225.medium.com/its-time-to-stop-using-sms-for-a...

[bduerst]

No matter what cellular service you use, you run a risk of being flagged as a false positive for fraud locks (irrespective of SIM swaps).

If a SIM swap scam is happening and your account is locked, it is incredibly unlikely they'll be able to swap it out.