I can close the thread with some observations now that I am back home in California.
With one visit to one shop in Aachaen it won't tell you much though! The Hunerbein shop had acres of larger trains and a small corner for Z with a display cabinet for new and another for used models. (but Z is very small right?) It also had a workstation manned by a mechanic with parts galore and a layout of all the gauges of track for test running. That blew my mind, you can take your train there to be fixed! Shopping was great fun, for me just being able to see something in person before buying it was cool. I found a few treasures, brought back an 88545 BR103.1, a used 86391car set and 82171 beer barrel car, an 89703 building and a Preiser figures set 88550. There wasn't really anything I saw that I couldn't have probably gotten (eventually) from suppliers here at home. And if you are paying the VAT you are not saving anything there either. The government has made recovering VAT a tedious process for shops, shoppers, and government officials alike. Way too much trouble for the small purchases I made. If I went back I would buy more figures though, at least the Preiser set I picked was half as expensive than they are here. One funny thing was while comparing my "short list" of the locos in the shop on my cell phone internet access when I searched the BR103.1 a Zscalehobo test run video on You tube popped up, with a chuckle I decided that it must be the one, even in Germany my California connection is helping me choose ;)
I considered taking the ICE train from Liege to Cologne for another expedition, it is only a 1 hour 6 minutes ride, but whereas Aachen is considered "near international" from Belgium Cologne would have required Covid tests and passport controls and after my experience I wanted no more to do with that so I didn't get to ride the ICE. A well, I can console myself with a model of one. I convinced my wife and her sister that Namur would be a fun visit but in the end it got scheduled on a Monday and the Marklin shop there was closed. Cool city though. I did get to go to a great museum near La Roche, Musee Du Chemin De Fer. They have a running steam engine there, but as we found out it only runs weekends :( so it is like two museums with the main station and the repair depot at either end of the line. At the repair end it was a ghost town, just us and the staff on a dreary Belgian weather day, and the staff let me climb all over their locos! I was in the cabs of a bunch of old engines, even with coal crunching under my feet, grease and oil and soot on everything, tool boxes everywhere and banging and wrenching from the mechanic staff, these are live steam trains!
Certainly a highlight for me as in the "proper" museums you can hardly see let alone climb under a loco.
Regarding travel to Europe right now I just can't recommend it. Obviously, getting sick and testing positive is a minor catastrophe, the quarantine requirements are demanding. If that happens you are finished. But every border and every airline and airport has different Covid related travel requirements, which change regularly, you have to be a wizard with a cell phone to even have a chance. I realize my experience was over the top, of my originally scheduled 6 flights, 4 were cancelled and had to be rescheduled or purchased from other carriers, at short notice at great expense. We will not be refunded by the DB and we still wait with fingers crossed to see if Vueling, an airline with no phone support and crippled internet access, will actually refund our cancelled flights (in their defense they did offer us a replacement flight home in late march 2022...) Twice we received Covid tests to travel and then were unable to get the results emailed to us without multiple phone calls and emails. It is not enough to know you have passed, border controls are only satisfied with papers, and it is rather stressful to be even momentarily be denied boarding because Belgians don't like Croatian documents. On a positive note the border controls are developed enough that governments have established protocols,
and the information is available, but then you have to deal with people who may or may not be willing or able to get things done in a timely fashion. I ended up getting tested twice (and paying twice) to leave Belgium yesterday. On the drive to the airport while struggling with the language difference the staff at the Covid test center in Liege flatly refused to try an alternate email address for my overdue results, saying that she had others to take care of and no more time for me. So I ran and got a rapid test at the airport. So have a back up plan if you do go!
I hope all this was somewhat enjoyable to read, LOL. This thread didn't turn out as planned but I hate threads that leave me hanging so I figured I would tell the story. And my wife says we just got our $ back from Vueling 9 days after the cancellation! Things are looking up :)