TL;DR: Cofounder of open source project says super popular platform using their project needs to pay up for inane reasons. Chaos ensues.
In summary:
WP Engine is one of the most popular third party platforms built on top of WordPress.
They have a link and images on their webpage referencing that they are built on top of Wordpress (this is legal).
The former cofounder of Wordpress said that they are illegally using the Wordpress trademark.
WP Engine sends Cease and Desist.
WordPress Cofounder doubles down, blocks WP Engine and demanded WP Engine pay licensing fees for using their branding.
This pissed off a lot of people.
WP Engine sues. For a lot, including extortion, abuse of power, and asserts the cofounder of WordPress has criminally made false statements to the IRS.
The Executive Director for Wordpress resigns, presumably in solidarity with WP Engine and the community.
It itself is not FOSS, but Network Chuck just had a decent video on setting up ThinLinc for his editing team. I believe it is free for ten or fewer users. There is an admin function that allows you to observe what another user is doing (session shadowing).
https://m.youtube.com/watch?v=qdo5lMR1lX4
In general, for native FOSS, I’m pretty sure you can specify the screen port in VNC, and connect multiple users to the same port, but you’d have to double check the configuration file. Can likely also be done with XRDP.