the communication between plane and wifi/entertainment system, if there is any, is almost certainly one-way. likely, the wifi system providing this info is receiving data from the flight systems and repeating it or transforming it a bit and providing that.
it would not surprise me at all if the flight attendants have to program everything about the flight into the system prior to departure each flight, and there is no communication from the aircraft at all.
(I guess there's some kind of firewall, but we know that those are not always perfect)
There could be some fuckery via shared power or other non-data systems but that’s probably beyond someone sitting in a seat with standard laptop hardware.
That would prevent any need for direct connection between the systems.
Is that how it works? I doubt it. But it could be done.
1: https://www.tsb.gc.ca/eng/rapports-reports/aviation/2020/A20...