Offer additional anonymous payment option - paygarden.com
Utilize paygarden.com for anonymous payment. PIA uses it with great success. Can buy gift card with cash.
Mike Smith shared this idea
Please provide a payment method to accept gift cards to subscribe to Proton services. This is a great privacy protection method since gift cards can be purchased with cash. For example Private Internet Access uses Pay Garden. Yes, such a service charges a fee from the gift card for the payment conversion but that is just the cost of privacy.