No pre-departure test, and no test on arrival. As long as you're fully vaccinated, no quarantine. The requirement for travel insurance that covers COVID-19 is still there, but no mention that you have to buy it from the government, your existing travel insurance should be fine (no idea if this requirement is actually being enforced, either).

I didn't get quite the same impression you got of Cambodia. As always, your experience of a place depends on how you approach it. Angkor is indeed crowded, but there are many other temples dotted around Cambodia with no tourists at all. Sihanoukville is awful (more Chinese mafia than Russian), but I had a great time on Koh Rong Sanloem just off the coast there. Everywhere I went people were friendly. I never encountered any hostility.