I would personally say that "easy" depends a little bit; if your device is listed on https://docs.mrchromebox.tech/docs/supported-devices.html then yeah it's dead easy to reflash the firmware and install any old distro and off you go. Anything not supported by that is a little more annoying because you need a distro that can deal with the default firmware's non-UEFI boot process. I'm very fond of my ARM Chromebook flashed with postmarketos, but it is a little less supported because of the boot process (and in some cases yeah hardware support isn't 100%).