Are you afraid of phone number related fraud? My personal opinion is that there's no need to specially get a new line to do sensitive applications such as banking 2FA. That's just my opinion.
I think it's ok to reveal your phone number, just need to secure SMS, your smartphone with virus scanner, use the more secured eSIM instead of SIM, fingerprint screen unlock etc.
It's just like it's ok to reveal your email address but not ok for strangers to intrude into your email inbox.
Similarly, identifiers such as NRIC, credit card number should of course be kept secured, but it's ok to reveal phone PayNow numbers, UEN, bank account number, etc for transaction purpose and lots of people revealed these to me to transfer money.
I follow the scam news on Straits Times, most frauds are related to revealing login credential, 2FA, CC number. Phone number related fraud that mandates an isolated mobile line is almost non-existence.