So the 2003 Accord EX V6 with 180k is back to running happily at the moment, more or less...

On the recent drive home I noted a bit of a slight squealy sound. After playing with the car to figure out when it was happening, it reproduces most of the time when i'm just drifting slightly to the right on the highway. On a 12 oclock clock face it's not even 1 though, more like 15 minutes... just the slightest little drift right... and the squealy happens from what sounds like the left front. I didn't notice the same sound from the right front unless it's harder to hear, and I didn't yet test at around town speeds (because I have a separate slow speed squeal which I assume either the brakes slightly dragging or being on the wear indicators on the front, but I thought the fronts were done recent enough it shouldn't have been the wear indicators...).

Would this probably be a wheel bearing? Or what else might it be?

 

Do some testing at slow speeds in an empty parking lot. It may be the same sound. Wheel bearing is more of a rumbling sound that will go away on turns.

Inspect the brake pads to see if the inside pad got stuck and is now worn down. If you recently did brakes, you may want to check the metal splash shield to see if it is rubbing on the rotor.

 

I agree completely with all the above.If you still don't find anything, you can, tape measure out the front tires to see if maybe the toe is off in the LF.