A checkout system that works with my firebase db?

I have a site built in HTML that sells a software and I maintain my users inside a firebase db.

My current checkout system is built on using POWR.io tools, where my checkout page has a POWR form that users must use to checkout with PayPal.

I started with this because POWR not only accepts payment but also allows me to collect emails and other form data which is absolutely necessary in this case.

I would ideally like to accept PayPal, stripe, credit/debit cards, and definitely expand into having an affiliate/referral system, discount codes, etc.

Is there a better payment processing system I can embed in my site that allows me to accept payment and collect data in this manner?

use paypal and a normal opt in theme .