The iOS one is unmaintained and has been for a while (it still doesn't officially support Godot 4.x). Supposedly it should be maintained again by EOY but we've yet to see any progress on it.

Maintaining this yourself is trivial. We sell IAPS on Android, iOS, Steam & XSolla in the Godot game engine. Android and iOS are the easiest. This is really, really minor stuff we're talking about here.

Maybe you can write a blog post or a reddit thread?

There were a bunch of people asking about it on Discord for Godot 4, and some confused reddit threads offering to pay people for a tutorial:

https://www.reddit.com/r/godot/comments/11vxeo7/can_i_please...

https://old.reddit.com/r/godot/comments/13ka6qc/will_pay_to_...