kosmos.social is one of the many independent Mastodon servers you can use to participate in the fediverse.
kosmos.social is run by the Kosmos open-source co-operative, and is open for new members via invitation by existing ones.

Server stats:

23
active users

In fact, GitLab explicitly state that non-profits have to pay exactly the same as for-profit organizations. Only exception is educational institutions.

Just in case you thought it's all hippie unicorns and rainbows over there. In fact, I have no idea why any non-employee would ever write a single line of code for them, seeing how hostile they are to actually self-hosting a feature-complete version that includes 100% of non-enterprise features. Group webhooks ain't no Active Directory support.