If someone wanted to take legal actions against The Solus Project, or a government wanted to submit an order against the Project, which the Project would not be legally able to inform their user base, what country would that be? In your case, the answer is simple: The United States of America.
Open Source, means, yes, you have contributions worldwide from developers worldwide. But ultimately, someone is accountable for the Project's legality, even if it is just a hobby run by a group of remote friends. That's the law in most countries. You cannot just argue, that the development is lawless and outside every jurisdiction on the planet. - Wish that you could, but that's not how the world works.
To answer your question, the list is not a long one. The United States of America has been a "hub" of business, commerce, and technological development for nearly a century. Ever current mainstream operating system (Windows, Apple, Android, iOS, and even Linux) originated from within the USA, plus the Internet itself. If there were ever plans for breaking glass in the event the US embraced fascism or proved to be less reliable, I doubt anyone kept those plans seriously, after so many years of dependability.
I, work for Meta (Facebook), and I can tell you we're now monitoring anyone who uses the word "protest". I am actually very uncomfortable with how closely, and in what manner, we're working with the current regime. Through my work, I have learned of a lot of business now working closely with the current regime. But it got me to thinking, that perhaps developing a list of digital providers outside US Jurisdiction would be a good idea.
You can view the list of operating system's here (see UR). I use Codeberg, an alternative to GitHub or GitLab, but located in Germany. https://codeberg.org/Linux-Is-Best/Outside_Us_Jurisdiction/src/branch/main/Operating_System.md
