Platform-wise I'm pretty agnostic, but I'd likely to want to stick to full fat Windows or Linux as it'd be easier (for me) to run VMs inside (for testing purposes). Pi4 would work for me as well and I have seen someone setting up VMs within one but I don't need to go that small and with a little bit of additional size, I can get vastly more horsepower out of it, That said, it's the display that is stumping me. ... I'd like some sort of mount that could handle a 13.3 HDMI or USB-C monitor and doesn't risk me damaging the IFE monitor. The mini PC I'm not concerned about (just need to plug it in and place it under the chair or in the magazine holder (depending on what fits... ). Multi-media keyboard/pad (like the Logitech K400) would cover what I need (or I could add a BT mouse) or if I know the airline is nervous about radio transmissions, can stick with a small wired set KB/MS. The only real problem is how to safely mount a monitor (I'd happily go with a little smaller but not sure there are that many portable monitors that are also FHD). As you can see from the first video, they used suction cups which I believe will either damage or scratch up the monitor. The airhook looks nice, but takes the tray and has limited strength to hold up the monitor (although it should fit). If it could handle the weight, figuring out a table layout should be easy (technically if using a multi-media KB, I don't even need the tray.

Right now it's an interesting project since flying right now is not advisable (and I do have others to consider) but when we're back in the air...