Port to Backdrop

Hello,
I've done an initial port of Payment, Currency (v1) and Paypal for Payment to Backdrop CMS. Available at:
https://github.com/backdrop-contrib/payment
https://github.com/backdrop-contrib/currency
https://github.com/backdrop-contrib/paypal_payment

Would be very happy if you could have a look at this if you get the time please, and even more happy if you would agree to help maintain or advise.
Thanks