I recently bought a Pixel 8 for 500€, they got cheaper since the Pixel 9 was just released. If you want to save some money you could probably just buy a Pixel 7a which will get updates until May 2028 (vs October 2030 for the Pixel 8). Supposedly the 7 has better battery life than the 8, but in the end it comes down to how long you want to use it.
dom0 is the administration qube which handles the graphical desktop, i/o and hardware devices. So if you’re installing dodgy software in dom0 you go around a lot of the sandboxing that qubes offers.