This has now been created here - Unofficial alternative Joplin distributions
It is a wiki post so anyone should be able to edit it - maintainers of the distributions listed feel free to change your names on the post and add/remove links to any additional websites or profiles (including your Joplin Discourse profile).
I haven't gone deep into the Joplin Server stuff so if there are more out there feel free to add, I'm just not as familiar with the variations of Server that are out there.