Connecting Korean to Hawaiian at Incheon
 

In the near future, I expect to fly in Business/Prestige from SGN to ICN on Korean and then transfer to Hawaiian to HNL. Will I be able to check my bags through? I’ll have over four hours to make my connection, but I’d prefer not to have to collect my bags, go through customs, re-check my bags, and then go through security again. Would it matter if I took Vietnam instead of Korean?

I don't have experience with this, but from looking on ExpertFlyer both KE and VN may check baggage to HA. Whether or not it will actually work at SGN, YMMV.

Definitely possible on a single ticket, as spouse did so late last year. If separately ticketed, I don’t know.

It’s separate tix. The Hawaiian flight is with points.

All you can do is ask at check in. Because you're also at the mercy of the outstation agent. The problem is the separate tickets. They absolutely transfer any bags through ICN on one ticket, though.