Question came up, i was using my Explore Action as the empowerd Waywatcher (must not exhaust his Explore Action) and draw a Dungeon Card which instructs me to exhaust an action.

Can i choose my Explore Action?

I don't see why not. Empower says not to exhaust the next action you use. Exhausting an action happens first, before you spend success or roll dice (or do any of the other steps). So in other words, here is the step by step, using your scenario:

1: exhaust Orion's Hunt

You skip this part if you are empowered

2: spend success tokens

3: roll 2 dice, get +1 success and +1 shield from empowered, resolve success/nemesis/attacks

4: draw and resolve 1 dungeon card

Say as an example, you draw "Despair," you would take a wound, lose a success token, and exhaust an action. Since Orion's Hunt is currently ready, it is a valid target to exhaust (in fact, if Aid and Rest had already been exhausted, you would HAVE to exhaust Orion's Hunt since each hero's refresh action can never be exhausted).

5: exhaust a non-nemesis in the shadows.

6: your turn ends.

K, thanks for your reply.