I am confused by a one main aspect of your post : if you booked this with EK as a single itinerary/PNR, then it means EK has an interline agreement with K6 (Cambodia Angkor Air). Otherwise, you can't book this as a single ticket. Furthermore, in case you would have to go landside, you may need a visa to enter Vietnam, depending on your citizenship.
I have flown K6 many times, and I thought the only interline agreement they had was with VN. But it may have changed of course.
If you really have everything on the same ticket, your connection is protected and bags will be checked through final destination.


I checked and K6/EK have an interline agreement, including for bags, so you'll be fine
Screenshot below is from ExpertFlyer for K6 interline agreements :



And same result when looking at EK's interline agreements regarding K6.