Methods to refer to threads in archives besides Google

Hello,

While configuring my Gnus to search better when referring to threads
I stumbled on the nnweb backend.
Looking at nnweb again made me think isn't there any other source that
could use the nnweb backend such as one that uses mailman archives?

Another thing that I learned sometime ago are public-inbox archives.
Wouldn't those be perfect for Gnus to search in? Some of them are just
plain IMAP making them very easy to adapt into Gnus.

I'm just speaking out loud here so to say. Maybe there's
someone else having thought of this or have some ideas around
this issue.

Have a great week,

Björn