The kernel is copyleft (100% of it).
Technically, sort of, but GPLv2 isn’t good enough. Stuff has to be GPLv3 (or AGPLv3) to fulfill the intent of protecting the end user’s right to control their machine. That’s the essential thing people are looking for when they choose “Linux” — if it’s a tyrant device like a smart TV that’s subverted to work against the user by showing ads or whatever, nobody gives a shit if it’s running a Linux kernel because that fact doesn’t actually help them usurp the manufacturer’s control.
Usurpation of control is what “GNU/Linux” implies. The fine details of which software has what license isn’t the point; whether the system as a whole delivers on the promise of user freedom is.



There’s also Ubuntu (which is even less cool than Mint, i guess, but nevertheless exists).