So... I've done that May 2023 for a holiday trip.
I left with my RPi4 and few gadgets but no Internet.
There I built https://git.benetou.fr/utopiah/offline-octopus/ and my main take away is
- you can build what is missing
and more importantly the meta take away is
- you need to iterate preparations
because just like first aid you need to be actually ready when needed and knowledge change over time. You need to actually try though, test your setup and yourself genuinely otherwise it is intellectual masturbation.
Have fun!