If I were starting a Mittelstand today, yes one great option would be to take YC's funding, take little to no additional capital, and exit as a Mittelstand with most of your equity.

But having gone through YC in W15, they're definitely not built for Mittelstands. YC pushes you to keep iterating and changing your pitch and product until you're targeting a multi-billion dollar market.

I do believe there's room for a YC for Mittelstands:

Be like Paul Graham circa 2005 – find people who others didn’t think could be founders and coach them from the very beginning to control their companies.