I've got a 10 Pro Fold that I've been using exclusively with GOS since the week it came out. I love it but also agree with most of the criticisms. Foldables are still a relatively niche product; I'm not sure they're right for most people. I'll answer your specific questions and then give my overall impressions.
traveller When comparing to Samsung Z-Fold 7, Pixel Fold is like years behind.
I wouldn't go that far. Z-Fold is slightly (very slightly) slimmer but has much worse battery life and doesn't have dust resistance. I've been foldable-curious for a few years now, but IP68 is what finally pushed me over the edge. I go to the beach a lot and trail run daily, so I need something at least moderately durable (YMMV of course).
traveller I also experienced weird display glitch right in the store, when it lost inertia and got barely responsive, and was "fixed" by rebooting the device. And this is the official Pixel firmware. I suppose AOSP/GrapheneOS degrades the experience even more showing various quirks here and there.
I have not had a single glitch so far. Again, YMMV. These are complex devices, and there's always a risk of yours suffering from Built on Friday Syndrome. Also, a store model is going to have had the shit kicked out of it.
GOS doesn't degrade the experience at all; GOS works perfectly, and all of the foldable features are functional: split screen with all the different ratios; the options for what happens when you close (immediately lock, continue, swipe to continue); and continuity all work just like the do on Pixel OS. I do not believe that there's a single foldable feature that you lose going from POS to GOS.
traveller do you still enjoy the benefits of a foldable and consider it's worth the price (around $2000) for this kind of device or would you rather wait out for the next year's model hoping Google fixes these and tries to catch up with Samsung?
It's not worth the price! The price is crazy! But I have the resources, I'm a nerd, and I like tech toys. That's it; that's the only reason to get something like this.
I spent a decade using phones for 4+ years (my last phone was an iPhone 13), and I had a few where I replaced the battery twice. There was effectively no innovation and no reason to upgrade frequently. Entering the "foldable era" probably means you'll want to upgrade every year or two before the tech settles in; it's getting better on a pretty quick cadence, so we're back to the advice that, if money is a big concern, you probably should wait.
traveller Also, do you experience other bare-AOSP specific issues with your foldable?
There are only two issues that I've experienced, and it's hard to call them "issues." 1) The GOS logo only appears on the inner screen during boot. If the phone is closed, you just get the colorful "G". 2) The four icons at the bottom of the screen (the "pinned apps" I guess you could call them) appear kind of close together on the left inner screen when unfolded. It's the most minor of minor UI bugs; I'm only bringing it up to give you a sense for how otherwise polished it is. :)
General thoughts:
1) The size is fine; it's about the same dimensions as my wife's iPhone 17 (not the big one) in a case.
2) It's heavy. This is the major downside. It feels miraculously light when unfolded, but as soon as you fold it, it feels 50% heavier than a normal smartphone.
3) Battery life is great.
4) Do not buy this to consume video; the inner screen is square, and almost all video is either 16:9/2.35:1 or vertical.
5) It is amazing for reading long-form articles like news and for ebooks. I absolutely love being able to unfold the screen and hop onto the NYT or whatever while I'm waiting; it's really delightful. I read way more ebooks now, too, because it's so easy to dip into them whenever I feel like it. This is why I got it, and it delivers 100%.
6) It's amazing for remote admin stuff like SSH, VNC, or remote desktop. Paired with a bluetooth keyboard, you can pretty much do anything.
7) The speakers are great.
8) Android apps generally suck compared to iOS, but the great thing about the foldable is that you can just use the desktop webapps, which are generally more functional and better than even the iOS apps. From a privacy perspective it's great, too, because it greatly reduces your reliance on apps generally. I keep very few apps on this phone compared to my old iPhone.
9) It's great for travel; you basically have an iPad Mini and a phone all the time.