I think e ink is all you need in a hiking phone as long as it has a reasonable camera (or perhaps none at all) and can display maps and books well enough. The trade-off of not having to charge for say a month is enormous value.
This one weighs only 47 grams:https://www.e-ink-info.com/e-ink-devices/mobile-phones
HiSense A6 is a new smartphone with an E Ink screen: https://goodereader.com/blog/smartphones-2/hisense-a6-is-a-new-smartphone-with-an-e-ink-screen
This one’s main screen is e-ink (which probably means the battery will last you a month: https://www.pcmag.com/feature/313023/hands-on-with-the-onyx-boox-e-ink-smartphone/1
More about this when I get out of hospital!
A reader writes: ‘ I looked this up and the fact that the frequency B28 wouldn’t work in Australia if you bought the phone (you’d have to get it from o/s). Has anyone advice on whether B28 is necessary or a must have?’
Steve: I was in hospital between back surgeries when I wrote this post and I have not been able to research it further. I guess hiking and other such off-grid (electrical) uses is not something mobile phone manufacturers have given much thought to. So far, for my own personal use I have not been able to better the Samsung Glalxy S4 mini: https://www.gsmarena.com/samsung_galaxy_s4_mini_i9195i-7468.php at 107 grams. I just love this little phone. I would like a better camera in it though and wonder whether I can fit one in somehow. I have (deliberately) done quite a lot of mobile phone repair on this phone. It is surprising how much of the phone is just empty space deliberately filled with plastic which can be dremmeled away. A few years ago someone tried to make an e-ink tablet just for hikers. Unfortunately it failed and I can’t even find it on Google any more. I thought it was called ‘eric’. Cheers, Steve.