There used to be one called #Tilt, but development stalled years ago.
There's a #crowdfunding plugin for #Wordpress called wp-crowdfunding. Don't know if it's #FOSS, although it seems you need to shell out $ to offer more than one reward and it only seems to offer #Paypal for payments. I'd love to see other options (#Monero?).
Given I heard WP now federates on the fedi, I imagine this kind of would, too, although I'd love to see something more native Fedi with AP updates etc.