I believe this is the project that has the Rust code (on the GitHub of ATProto)
@smokesignal.events/acudo at main · tangled https://share.google/HG59BdzeJpib7fw5x
I'm assuming easier to spin up a new instance on your own, but this is my personal opinion.
I'm wondering though - after creating an event, how does one see the list of who has RSVPd to attend? I can't seem to find any way to see this info.
API's are always a good thing, weather they are private or not.