"AFAIK in Germany the TL;DR is that if there's anything in the EULA which violates "German Civil Code (BGB)", then either parts or all of the EULA are invalid. "

There is nothing unique about German law here. The same is true in the USA and most other countries. If a EULA or any other contract (whether agreed verbally, signed physically, digitally, or via a "click") violates the law, it can be considered invalid/unenforceable. It has nothing to do with how the agreement was agreed to, but with what the agreement contains. (There may be some legal theory that may carry some weight that a contract agreed to via a "click" is more likely to be unconscionable that one agreed to with a physical signature, but that does not automatically make all "click" agreements unenforceable.)