I’ve got a couple of options. I’d never read non company material in flight, but if I did I’d read a book. Currently trying to get through the first book of the Malazan Book of the Fallen series. This is like my fourth attempt maybe this time.
People have mentioned you can get ebooks from the library, but Amazon also has this thing called kindle unlimited. It is subscription based but the cost is negligible. What’s fun about it, is it’s predominantly self published stuff, and there is a lot of junk on it, but there also some absolute bangers. It’s been an entertaining hobby in of itself reading through some of the junk to find the treasure.
I’ve also been doing some solo role playing and journaling games.
If neither one of those hit the spot I’ve been playing this sci fi 4x game recently at home. Well I say 4x game, but the program itself is really a spaceship design and logistics/organization simulation with 4x elements to let you use your ship designs and TO&Es. So I’ll make planning notes, designs, and general organizational plans for when I’m home.