...and by using a throw away protonmail account, now a third party knows that you are getting a phone number. Better to limit your exposure whenever possible.

Sure, maybe you have no choice sometimes. But sms4sats is free if it doesn't work, so try them first.

nemo

Unlike textverified, sms4sats doesn't need you to sign up for account. That's a huge privacy advantage. And frankly, getting a temp phone number shouldn't require an account anyway.