Personally I haven’t. While Linux is imperfect, choosing the right distro makes the rest of the experience straightforward. And with it’s whole complexity, I find Linux more user friendly than Windows. Even driver issues, broken shadow file ownership and KDE specifics only made me more confident about my choice to use Linux after I solved everything.
Available only on select Pixel phones, and the virtualization API that makes it possible is available only to preinstalled system apps.
So no, you cannot install Ubuntu image onto your Samsung phone, you specifically need to buy the newest Pixel.
You can use termux and some other thing to run Ubuntu on a Samsung, it’s just not built in Iirc Samsung has some Linux thing with dex