(Tailscalar here) To be clear: it's only the GUIs that are closed source on selected platforms.

I stand corrected.

Although, the problem is not so single-layered. Do I understand the situation correctly, in case of iOS, to not be subject to additional limitations of the platform that restricts the distribution of your products to the extents that the laws of the countries where your business is registered require, all the user has to do is to fork the main repo (which is, thankfully, BSD), build a minimally acceptable GUI, pass Apple certification, publish the app in the app store, and Bob's your uncle?

Thats actually a good way to split a project up into closed/open imho. Open the functional part so people can see you're not sending data to hq behind their backs and make the boring time consuming ui closed. I like it. Then make money out of a service rather than the software. As we all know, tech people will see a piece if challenging software and go out of their way to replicate it and release it for free, for whatever reasons. So open sourcing that part takes the challenge away.

Does that include android?

can you say more about this. I've been considering adding tailscale to some products but if my (nerd) perspective is to survive corporate realism I need more than a 1-liner to justify. seriously curious. Also how would I pitch it to a EU based crowd that wants increasingly less to do with US based tech?