That are a handful of platforms that have $500 minimum investments, like CalTier and
Collab, but if I were you I would look at options that would allow you to spread that out among multiple investments.
Arrived Homes, for example, lets you buy shares of rental properties with a $100 minimum so you could add five properties to your portfolio.
Landa has even lower minimums, so you could potentially have 10-20 properties under your belt with $500.
I think the important thing, no matter how much you're starting out with, is to keep adding to your portfolio over time. $500 might not make you rich, but with $500 now plus $100 next month, $100 the month after that, and so on - you definitely can start building some real wealth through this.
As you can probably imagine, the dividend income you'll receive from a $500 investment won't be substantial, but if you continue to reinvest those earnings your portfolio will grow faster and you can start earning some substantial passive income.