External programs can now set a seating layout by first setting the relevant PAXFLAG{}_DESIRED Local:Var with a bitpacked 64-bit long number, i.e. 7, or 1111111 would set the first 7 seats in a passenger section (station) as seated, then start the boarding by setting the BOARDING_STARTED_BY_USR Local:Var as true. This will start the boarding process as though it was triggered by the EFB.
Note: This could be impacted by the pending panel.xml configuration topic (if implemented), right now configuration is in the EFB loadsheet.json and just hardcoded in rust which is not ideal obviously.
Documenting new bitwise flags passenger simvars introduced in https://github.com/flybywiresim/a32nx/pull/7442