Add More Payment Options

Do you mean payment gateways or do you mean different pricing options?

Pricing options.

Working with a non-profit that has 15+ different offerings.

Pricing options.

I am working with a non-profit that has 15+ offerings.

Basically returned to PayPal and used their button generator – copied the code and added my own CSS.

You can have as many pricing options as you want. Use the shortcode for it:
https://www.tipsandtricks-hq.com/wordpress-easy-paypal-payment-or-donation-accept-plugin-120

I must be very thick, but I dont see how can I create different buttons for different products / services within the same website?

sorry…

To be clearer, I would like to have these buttons I have now in a separate html page, as part of the main WP site.
https://artbash.co.uk/payments.html

does that make sense?

thanks for the patience