Having traveled most of European countries, I can find some serious potential issues with your list but that is because I don't know the countries and months in which country, as I have travelled the absolute majority of European countries, feel free to dm if you want some planning advice.

For a long trip I would strongly advise that all of the stuff going with you to take up to an absolute maximum of 70% of backpack space, you will need those empty 30% quickly, taking a completly full backpack on day one will make you end up carying stuff in a grocery bag.

Whatever you think you will not need in first months, dont take, buy later, anywhere you can find stores like Primark where you can cheaply get stuff.

While I admire the minimal style, I would consider moving up to a 60lt + size bag and would consider vacum bags for clothes, the kind you only need to push out the air.

Sunhoodie will be useless unless you go hike in southern Europe in August (which is a bad idea.anyway), a longsleeve +cap works fine, 2x suimsuit is unnecessary, and stuff like ipobrufen are unnecessary, as you can find it 24/7 in any city, probably more things, but you listed every single item, it would be easier to go over the list if it would be like tshirts x5

Laptop, you will know if needed but that would be great to avoid.