I have bought some good quality merino stuff from https://danishendurance.com/

Also in Germany

Still sounds implausible and far fetched. Why would you be outside without adequate clothing? (Also below zero can be fine in jeans and sweatshirt if the sun is shining and there isn’t much wind). And in that case it would be more a heat issue and less like a shelter issue.

The other case also sounds more like a heat/water issue and less like a shelter issue.

0°C is completely fine with jeans and a thick jacket, especially when it’s sunny and there isn’t much wind. It’s cold, but there’s probably not much ice or snow, if anything, probably mostly slush.

Compared to say -20 C where you should have a good ski jacket and ski pants, warm shoes and socks, generally multiple layers everywhere, winter gloves and so on.