I take my android phone with me on airplane mode. Maybe I should turn my phone off completely .. There is an offline map app "Here we go" which I can't trust completely but it at least has to collect data and upload it later (I never really update it though).
I bought one of these before Anarcapulco '18 => librem-5 .. I have been waiting a lone time. If I get it soon enough maybe I'll have something I can show people. Otherwise, I'll be carrying a pen and paper around taking notes again. lol
I used to get those tiny, around five-ish CHF samsungs when they were more common in Europe ... upgraded a bit since then ... but not much.
I'm still primarily pen and paper when traveling. Too spoiled with desktop replacement laptops to use anything else much ... Had access to laptops since '90s ... maybe spoiled.
Just buy dense paper and especially dark ink pens and have fun ...