You can get free or very cheap health insurance in most of the US if you have low or no income, including if you're bootstrapping a startup. "Most of the US" means the dark blue states in [0] plus Wisconsin.

[0] https://www.kff.org/medicaid/issue-brief/status-of-state-med...

Even that can be finagled by paying yourself a below market salary and signing up for Medicaid.