There're accelerators that take in applicants pre-idea, pre-team pioneered by Entrepreneur First(https://www.joinef.com/) from the UK. The cohort size is about 100, and the founders come from diverse industries and backgrounds. It vastly increases the odds of finding a co-founder - a person who has complementary skills, is committed, and wants to start the company at the same time. Though the thought of starting a company with a stranger can be hard to fathom, you have 3 months to test out the working relationship with different people before committing.

Disclaimer: I found my co-founder from the EF program and completed the program.