No idea about Pixar keys but GC keys open up the gates to enter DH grounds from all of the various paths and the same the other way to get into the GC. Not tried them on the pool decks but they do get you into the grounds no problem. I usually have to tour the gift shops of both on most trips....
I'd just look around here on both the VGC and VDH threads and ask if any fellow members who have perks are there during your visit and I'm sure someone would be happy to meet up and get you into the lounge if you wish. The coffee machine is fairly good
And about that TOT tax thing - I've found that by switching my brain to VDH = more frequent trips in a studio (garden please) it makes the TOT a bit less of a burden. Also, the free parking helps (yes I know we get that at VGC too) as it's $$$$ for regular guests who are also paying more than me to stay there and also paying way more taxes/fees. The TOT was the price Disney had to agree with to get the city to approve adding 300+
DVC rooms to the resort which ultimately gives us owners a lot more options as VGC is so few rooms.
You may want to do some research into the various assessable duos. Some of them have unique layouts and beds that are "real" (not murphys) and what seems like way more space. We had to ninja one for me and
@MrsNVDISFamily for our quick trip to visit
@UrsulaWantsYourSoul for his party/GV open house. We very much liked it for a short trip for just the two of us. Plenty of space for a few nights.