Debian does just work and is a good choice. I think people typically have good experiences on Mint also. Ubuntu is becoming like the Windows of Linux distros, I used to use it on everything but I won't be installing it on another machine because of Snaps.
If you plan on using Linux to do gaming you might want a more up-to-date distro tho.
We are already (mostly all of us) stuck with one company's systemd. We're already on some portion of what you're describing. As long as we use FOSS I think somebody will be able to fork any software that starts turning to shit with ads, LLM everywhere, spying on your activity, etc.
They are. It is a huge problem that companies are allowed to do clickwrap bullshit with no human-comprehensible summary. But people are agreeing to this stuff.