If you don’t trust the software (you could just use Wireshark or similar tools to check whether it connects to the internet at all), then yes, that would work.
Yes, please provide details of their dishonesty. We've seen their EULA, your questions regarding it, but you having problems with ELUA does not equate to dishonesty
Having red flags is not the same thing as a company overtly looking to lie and be dishonest as you state.
If the file manager is free you can simply block all internet connections and just have to update always manually by downloading the latest version.
If it's not free it might check the registration once in a while or at every launch and you can't block all connections. But mostly the name of the connection responsible for this is obvious. But you never can't be sure if this connection is used for other things too.
I can't decide what file manager to use. I installed all of them and somehow always get back to Finder. Those several Commanders, I just always forget to launch them. And when I put one of them in "launch on login". I forget it when it's minimized.
I need something that is replacing Finder completely like Xtra Finder, Total Finder or Path Finder. But those were not very stable already with Sequoia. They even run in macOS 26 more or less. I hope for an update. I'll try all three again in Beta 4.
QSpace supports that. When some other application offers something like "Open in Finder" and I use it, QSpace opens. It's a QSpace setting to replace Finder, just as it is in Path Finder. QSpace can also replace your desktop.