I have a Patagonia rainshell which I found dirt cheap on sale many yeara ago and it is absolutely fantastic. Packs small into its own little puch and the water repellant hasn’t failed me yet

Dunno if available in Germany, but check out if t-shirts from Northern Playground are available.

They are a blend between merino wool and silk, with a nice and loose fit. Their tees are my favourite, but also offer longsleeves and grampa shirts, socks, beanies, etc. Sustainable, made in the EU, really great products.