"The reason OpenSats feels different is the way that it is running. It's not any one defined piece of software."

Sorry to be pedantic but this isn't new either. FSF was originally set up as a legal umbrella for the GNU Project, which covers many pieces of software. Software in the Public Interest was set up to umbrella Debian, which also includes many software projects. Software Freedom Conservancy forked off FSF to do a similar thing. Apache was set up for the webserver, but now umbrellas dozens of other projects.

Running a 501c involves a lot of administrivia, so it's unusual to maintain one for a single software project. This is why platforms like OpenCollective and Liberapay were established. So that new projects could accept donations to cover expenses, without having to be formally adopted by a 501c.