Apple's CFO, stated that the EU countries make up about 7% of Apple's global App Store revenue on a shareholder call. I can't think of a reason that the EU's percentage of App Store revenue would be any different than it's percentage of iPhone revenue, and I've asked in multiple threads and not gotten a good response (just claims that he "misspoke" on a shareholder call - which ignores the fact that Apple didn't correct the record which they would be required to do on that call.)
Also, the UK and India rank reportedly #3 and #4 in by-country revenue (bigger than France and Germany, for example). Both are outside of the EU but included in Apple's "Europe" market segment.
The list of countries in Apple’s “Europe” market segment can be seen on Apple's
latest 10-K on
investor.apple.com - it's on Page 5 of the 2023 10-K.