It's not really 2FA even. More like a magic link (which is what we use for verification via email). The customer has no password, just verifies using a code via sms/email.
It’s for the booking site so most visitors come to make a booking thus conversion rate would be high generally. We never had passwords there so can’t compare conversion rates.
For signups to our app (to get an account with a booking site) we require a password.