I occasionally use CBN for sleep, never THC, so maybe it's different, but I quickly develop a tolerance, like within a week of daily use and have to cease for many days or a few weeks to get any further benefit at all.

As I read, the endocannabinoid system in the brain is pretty homeostasic.

Does something similar happen with cannabis munchies subsiding to people who ingest THC or whole leaf products daily?

Yes, but it remains a good anti-emetic.

I've been taking CBD daily in the evening for sleep (can't find a quality source if CBN where I live - I am interned tho, the research is compelling for sleep) and I find it can act almost like an appetite suppressant.

Anecdotally yes. I'm a very occasional user now and get insane munchies but when I was using it differently I felt that tolerance built quickly and I stopped having munchies once it did. Not even quite daily use either like 3-4/week. Another comment elsewhere in here describes the same experience.

Once you become a heavy user it no longer reliably triggers appetite, maybe because you get better at recognizing the hunger is fake and focus on other aspects of the high.