Great question - I too would be very interested. I briefly looked at what could be accessed easily a few months back but didn’t get far and didn’t have much time to look into it so haven’t pursued further. I remember >10 years ago there was a way to access SABRE and possibly other systems via internet and a ‘home travel agent’ type account but I can’t remember the details but believe that access method was withdrawn. Perhaps Steve Biddle could provide some info in regards to your question - I’m sure he would be well informed about options in this space if any exist.