nlnet is the main one that comes to mind.

Perfect, now you just have to wrap your program inside a debugger in production!

Yep, that’s the gist of it. In order to change the license from the GPL, they’d need the permission of all of the copyright holders who’ve contributed code under the GPL to the project. After a few months have passed, this basically makes it impossible (or at least extremely difficult) since at least one person (and likely many people) will say no.

They have also funded a lot of improvements to XMPP clients and servers.

Along similar lines, I’d say Snikket. I feel XMPP often has quite a bad reputation based on the user experience from 10 years ago, but it’s come such a long way and projects like Snikket make it very easy to get started.