That’ll be in the next feature I guess. I think the main idea initially was to show people their own events before booking available times and before invitee accept the invite too. It’s a simple feature that I found missing from calendly

However I see the point where people might not have google account (or other services)

framadate looks more like doodle? This is seems to be for booking appointments, e.g. small business owners could use it so that customers book appointments.

The cool thing, this could likely be extended with other calendar systems as it is OSS. I assume the author just scratched their own itch first.