Indeed payment module already adds a website_published button to ease
acquirer management directly in payment without link to website. The
mixin added in website_payment adds a website_url field that has no use
for payment acquirers and is not used at all in the current codebase.
As there is no website url the website publish button method is not
different than the one already implemented in payment. There is
therefore no need for this override, lessening model code in
website payment.
Sale orders created through the website that have to be automatically
invoiced should ignore the delivery invoicing policy.
Otherwise you can end up with either an invoice not being generated at
all. This means the user has to manually generate and add the payment to
it. Even worse is if only some purchased products have invoice policy
delivery. In this case a partial invoice would be generated to which the
payment would be added, leading to a mismatch between invoice total and
payment amount.
Thibault Delavallée