Imho, it doesn't make a lot of sense. You can't compare this to being a founder of a startup vs being an angel investor in multiple startups coz of the level of active day-to-day involvement.
A PM will have to get involved in the daily business activities. It's not just about a financial investment for a PM.
Thinking from the startup's pov, I feel they'd want their PMs to be only their PMs.
All that said, you could explore being a fractional CPO for multiple 0 to 1 startups but that would mean doing it all under your brand name as an expert and not as an employee of an incubator, so to say!
PS: I might be wrong. Only your end users can tell you if it'll work or not. Cheers!