This advice from the crypto-universe comports with what @tqbf and my security friends have been saying for a while: you really, really don't want anything you care about at the mercy of a $CELL_PROVIDER customer support rep.
Get a Yubikey and put it on the important stuff.https://twitter.com/DoveyWan/status/1089403666354778112 …
I don't think this is accurate; I swept all my Google accounts for SMS options and deactivated them all.