A list of countries Cambodian passport holders can enter without a visa has been released. Obviously it’s not a great time to travel, but once the COVID-19 virus pandemic is done with, bear in mind a Cambodian can stay in Panama for 180 days without a visa, or Gambia and Ecuador for 90, or a 3 month break in the well-known tourist hot-spot of Haiti.
If you have any idea where Niue is (Niue is an island country in the South Pacific Ocean, 2,400 kilometres (1,500 mi) northeast of New Zealand-according to Wikipedia), and you can get there, then 30 days visa-free is probably enough to explore all 261.46 km2.