I’ve been in these three cities in late 2021 and early 2022. In September 2021, Rome, Milan, and Venice, I found that Hermes boutiques were extremely crowded with locals. As a walk in tourist, i found it difficult to get an SA to help in RTW and fine jewelry, never mind bags. Bags were flying off the shelves (in Milan there was a single rouge H mini Della cavalleria, and when I went back the next morning it had already sold.
Paris, I believe, requires an appt for a bag, but there are stories of TPFers getting lucky. If you want to try your luck, I advise trying to ask an SA if it’s possible to get a non BKC without appt. (And, I would try to do it out of earshot of anyone else).
i think London is your best bet. DH and I bought some things at NBS, but Cadogan Place was the nicest and friendliest. As a walk in, I was offered an etoupe geta chevre, but I politely declined. The same bag was on display, but not available to purchase, at Harrods. the London hermes at heathrlw also was very well stocked. But, there is no VAT back.
These were just my experiences. Perhaps someone will post more recent ones. have a wonderful trip and happy shopping!