Purchasing a high-end Swiss watch while visiting Portugal?

Up to now, I have never purchased a single watch from a watch boutique.
They have all come from this website or from online dealers ( usually trade-ups )
I will be spending a few weeks touring Portugal and Seville, Spain this Fall
Are prices for Swiss watches less when purchased in a European Union country than they are in the states?
Thanks.

I wondered about this on a trip to France (before the recent tariffs). I priced the new FOIS at the OB at Gallerie Lafayette in Paris, and found the base price to be close, maybe a bit lower than US prices. In addition, the VAT refund further reduces the price if you are non EU resident. VAT rate is 20% in France, but you will not get the full 20% as refund, more likely in 12-15% range, which is still substantial. I believe Portugal VAT rate is more, maybe 23%, so the refund may be a bit higher.
So you need to know the price of the desired watch incl sales tax in US, the price in Portugal minus the VAT refund, and the cost of importing the watch back to US on return at the border- which will be 39% or more. So its hard to justify buying in Europe on a financial basis, as you will be paying a premium for the "experience". Even before the recent tariffs, it was not worth it, but now its much more costly IMO.

Edit- and one more consideration is of course the currency exchange rate, which can influence the math but not likely enough to make this worthwhile.

In reality, I would say the number of people declaring a new watch upon physically entering the US today and paying the 39% tariff is somewhere between nil and none. I'm not saying one should do this, I'm just saying what's happening today.

The era of scoring cheap Swiss watches at 40-50% less than retail is long gone, done in by the Internet and generally strong Swiss Franc. Say 2000 onward.