I've taken NyQuil while using the Seven+ a few times, and it contains acetaminophen. For me, the CGM said that I shot up to 400+ mg/dL for a few hours and then I "dropped" like a brick back to where I started. I was paranoid the first time this happened, so I was doing finger sticks every 20 min or so to reassure myself that I was still in my target range. I haven't taken anything with acetaminophen since switching over to the G4 Platinum, so I don't know how it reacts for me.
I don't think hydrocodone will affect the CGM accuracy, though, since it's not acetaminophen, but I'd be doing extra checks anyway. You can always check with the doctors and make sure, and if it is a concern, you could always ask to have the medication switched.
Good luck on the surgery!