I don't wanna spoil your day with a blackpill, but if the US government want to find you hard enough, it's very likely they will succeed. Search about the security issues of Intel ME and AMD PSP. You're only safe if you're using a 15yo hardware with modified firmware, and I'm only talking about one vector of attack. There are also other documented stuff, like using the wires of your machine as an antenna to send data without internet and stuff like that. It's hard to hide from an organization with an infinite budget and a lot of smart people.