Another suggestion if my other one wouldn’t be an option.
How about creating a special account that groups have to use instead of a regular user account?
Kind of like a social media business account in a way, they have a page where they can advertise their services instead of here, there and everywhere that’s mostly inappropriate and unrelated to the topic they’ve decided needs their advertisements.
They can easily be found via a special search which will list all of the groups.
They can’t post on threads!! There would be no need too if they could easily be found as could their examples but as they aren’t right now, they are everywhere. Some are closed, some have disbanded e.t.c But no one knows.
All of their request work could be done via private message.
People can still easily recommend them and what have you but at least it would be organised and dignified (unlike right now). But groups would have to use a business account, not a regular one.
Again, if this is in the wrong place or named wrong, my apologies.