Porting Payment Modules from other carts

[torvista]

Given the decline in ZC, payment providers generally do not offer a module for Zen Cart.
They may offer for Magento, Prestashop, Opencart, Woocommerce, Virtuemart, OsCommerce, Drupal Commerce, Shopify...

Evidently osCommerce would be the most obvious starting point, but after that?

...anyone got some experience to offer as to what platform may be the most "understandable" for a ZC user to modify?

[OldNGrey]

One to try is SecurePay Payment Gateway also known as SecurePay XML [ https://www.zen-cart.com/downloads.p...2144&styleid=2 ]
The latest is in my GitHub [ https://github.com/OldNGreyBMR/securepay-xml ] and it works with ZC158 and PHP 8.1

I have found that I have only had to make minor updates from the original code to keep it working.

OldNGrey
Prod: Zen Cart 157d; Apache 2.4.41; PHP 7.4.3; MySQL 8.0.27; Ubuntu 5.4.0
Dev: environment Pre-prod: Zen Cart 158; Apache 2.4.47; PHP 8.1.9; MySQL 10.4.17-MariaDB Windows NT 10.0 AMD64

[torvista]

Thanks but I am not asking what payment provider to use, I'm spoilt for choice on that.
I'm asking if given a selection of pre-built modules by that provider, what would be the most understandable/better starting point for building my own module.