You might be familiar with their rants claiming to be an "American National". This is differentiated from a "citizen" mostly by birth location. So a citizen is someone born to a US citizen parent or born in a US state. A "national" would likely be born in a US territory like American Samoa and Swain Island.

The below goes into further details.

https://govassist.com/blog/us-nationals-vs-us-citizens-uncovering-the-key-differences-for-travelers#:~:text=What's%20the%20difference%20between%20a,U.S.%20territories%20like%20American%20Samoa

I'm pretty sure US Nationals can get passports, but a true National likely wouldn't be getting their info from a sovcit group.