Removing the credit/debit card information for registration is a good move. But after the "promo" period is over, will you bring it back? Honestly, I don't think anyone would feel safe if they need to input sensitive data right at the gate just to make an account. You can probably make a "free" tier where people can simply log in and check the last few data, so they will have to pay to access the full data to get the full picture. If that's not possible, then simply removing the credit card for registration would be better.

I'm not sure if it is possible but copying Mullvad's model of business sounds good too. They don't need personal data and just provide an account number to register and log in, and then the user needs to pay if they want to use the service. With how people's awareness of privacy increases, it might be worth a shot to look at it. Just my 2 cents.