I myself haven't seen any 8.5 cars that I can think of on the road, just of course in the dealerships. To be honest, I don't really see a huge number of 8's around either, but I guess I am not really looking for them and unless they're a performance model such as the GTI, I don't think I am going to really notice. At night with the light bar across the front, they are a lot more noticeable!
As for the GTI, the dealer didn't have one when I ordered my car, but do now. That is the only other one I have seen in the flesh. There was a stock in the country on the VW site around September time which depleted, but I think that is building up again now. There are some cars out there, but across the country, I would suggest very few.
My old 2018 7.5 GTI I owned from new and financed for a year before being in the fortunate position to pay it all off. That car did me really well and allowed me to put a big deposit on my new 8.5 GTI, so my monthly payments are quite low on PCP. I will keep this car for a long time and will pay it off after the initial PCP runs out.
Loving the 8.5 GTI currently. Running it in at present, but I do think the DSG gear change is much better, more predictable and quicker. Probably just a better software map, but is an improvement for me. You can see where there have been cost cutting changes with little details and some of the quality which is a big shame. Nothing to get too upset about, but that VW quality has reduced a little. The Infotainment is very different from my old 7.5. Lots of changes and I really like having wireless Carplay. I notice you can buy and install 'Dynamic Background Lighting' from the VW shop. No idea what that does really, but may try the 1 month trial at some point.
I have to say I am a little disappointed with the Harman Kardon setup. I think I was expecting more, but it does not feel and sound a whole lot better than my 7.5 standard audio. I read similar stories online and putting it down to the small sub. Maybe I just need to play with the settings more, but its not as good as I was hoping or expecting.