Anyone using passive income investments outside of stocks and real estate?

I've been trying to diversify some money that's currently sitting in a brokerage account, and it got me thinking about what people actually consider good passive income investments these days.

Most discussions seem to come back to dividend ETFs, bonds, REITs, rental properties, and maybe a few covered call funds. Nothing wrong with those, but it feels like everyone is looking at the same handful of options.

Lately I've been seeing more opportunities around private businesses, crowdfunding investments, and consumer-facing companies that are raising capital directly from investors. Some of them seem interesting, but it's a lot harder to evaluate compared to buying a public company.

For those actively focused on income generation, have you found anything outside the traditional stock and real estate routes that's been worth considering?

Not looking for get-rich-quick ideas. More interested in what people think has real long-term potential.