Things to consider:

Non-tactical Subdued Earth tones No molle on the outside Preferably worn-looking

That’s for the pack itself. For the contents, I’m sure others will come up with ideas too but here’s what I’d pack:

Water: A liter a day at least Food: get 2 24-hr MREs and empty the contents into the pack. The packaging takes up a bit of space Flashlight with extra batteries Tarp for shelter from rain A good knife Multi tool Fire starter and a waterproof tube of matches 2 extra pairs of socks and underwear A good pair of gloves IFAK

Optional: Firearm and ammunition

On the outside of the backpack, tie a good pair of boots (preferably waterproof) so you’ll always have them ready. And also get one of those windbreakers you can pack into a little sack and clip it to the backpack. Empty Hydroflask or alternative. You can keep snacks or utilities inside it too.