Re the "Payment Acquirer" not available comment, that occurs when the customer is not logged in.  To use that functionality also providing Portal access and having the customer "sign in" before approaching the Payment Link will have the payment acquirer issue go away.

Ideally this can all be built together into a unified landing page.  I have a series of OCA addons that I have added to try to make an acceptable "out of the box" solution.

Hi,

By default, in the action of sale order, there is option to generate a payment link by default in Odoo.

You can use it, as it is or change as per the need.

Thanks