As others have mentioned, it’s incredibly easy to install yourself. You just need a flash drive and another device with internet access.

If you’re gaming, I’m using Garuda Dragonized, which is set up for gaming. I’ve liked it and seen many others like it too. Regardless, KDE is probably the DE you want if you’re coming from Windows, but there are plenty of others you may prefer.

You probably can’t get it pre-installed, which I think is probably monopolistic if the only OS choice presented to customers is Windows. That’s how it’s spread so far, not because it’s easier. The issue with pre-installing is they’d either have to let you choose from a ton of options or just limit your choices. It’s easier to let the customer handle it.