My app already uses SMS verification, but there are two problems --
1) At first, SMS are not free (cheaper than in Firebase Phone Auth, but anyway)
2) User must type verification code from SMS-message.
Theoretically, I can read SMS, but I want to avoid permission requests, which are able to confuse user (READ_SMS, SMS_SEND etc.)
As I understand, Phone Selector and SMS Retriever do not require additional permissions.
I hope that Phone Selector, which, probably reads call logs and etc., is able to offer telephone number, which I can compare with typed by user.
If these numbers will be the same, there are no reasons to use SMS. Unlike SMS confirmation is more reliable.