I don’t fly enough to carry it with me, but an ultralight tent (nature hike cloud up 2 person) and inflatable sleeping bag under 2kg if you exclude the groundsheet. Not sure if security would try to wake me constantly even airside… probably yes but otherwise would sleep like a baby with my earplugs, noise cancelling headphones and eye mask

Probably: a YouTuber tried something similar[0] and apparently was not accosted.

[0] https://www.youtube.com/watch?v=DUHQ_lLD0n0