Change WordPress main function

I want little bit modify wordpress/woocommerce user’s: signup/changePasss/restorePassword – so I want complitly change email/password to phone/smsPassword.

I want put phone number like 15544554777 (wihtout “+” before number) into Email field of the WordPress database. Is it okay for WordPress and I’ll didn’t broke the system?

Or better put the phone number to phone number and the Email field should be empty ( my user will not use Emails at all, just phoneNumbers).