Gitea is not fundamentally different than Forgejo, Forgejo is just a better fork of it. Better in terms of: more contributors, more users, dogfooding (Gitea is built on Github 🤦).

But yes, GitLab is like the Mac of Git forges: everything is included, doing everything their own way, vendor lock, very expensive. There is a community edition but serious users will run into its limitations and it does not integrate neatly with external solutions.

Forgejo is IMO the Linux of Git forges: low on resources, expandable, hackable, stable.