Reservation System setup on JaaS

Can I connect Jaas to an external conference reservation system ?

Sorry, there is no such feature at the moment.

Is there any way to schedule a meeting in Jaas using a REST API ?

Scheduling a meeting with Jitsi Meet is just a case of agreeing a room name and a date/time. There isn’t any reason or need for the room to “exist” before anyone joins it.

If you want to restrict access to the room before or after the scheduled time, you can use a JWT with nbf (not before) and exp (expiry) claims.