It's ultimately your call on when to intervene, but I'd personally err on the side of caution and at least take the egg out to examine it. Peeping and moving are good signs, but has it been able to move its position within the shell?
You may get a better idea of what's going on if you can see it up close: if you see active veins or yawning, you'll know assisting is premature. Maybe the membrane just looks dry but is fine. A close look will help inform your next move.
I applaud your cautious approach and concern about the status of yolk absorption. Remember, though, that just because you take tiny steps like gently pushing a bit of membane away from the bill or slightly widening the pip hole to assess positioning doesn't commit you to a full assist.

You can always stop, put the egg back in the incubator, and let the duckling continue to work. Handling the egg may prompt the duckling to begin pushing again, and that should show you whether it looks like it has the leverage to get out or not.
Pete55's
waterfowl incubation guide also has helpful info. about assisting, and describes steps like freeing the head and neck (if blood vessels have dried up) but leaving the hatchling in the bottom part of the shell to absorb yolk, if needed, and kick out when ready. I use this technique, successfully, myself. There are photos near the end of post #1 in his thread.
Hang in there! This part can be nervewracking.