As you know, I use an iPhone (6S+) with the Mem-Map app installed. But I do USE it. Navigation, recording the walk, my sole source of photos and videos, occasional phone calls, email and internet news checks, maybe the 1 pm Radio 4 news headlines, etc. I revel in having that much capability in one relatively small device.
But, of course, I'm lucky if I can finish a 10 mile walk (with stops, lunch, etc) before the Low Power warning comes up. So I carry a power pack. Over picnic lunch I recharge from that. Or charge while walking.
My pack is a few years old and called RAVpower, Model RP-PB19, and its capacity is 16,750 mAh. I see there's a range here:
https://tinyurl.com/yd4bzwwl [nofollow]Of course, it's more weight to carry (mine is 320 gm), but I wouldn't be without it now.
Suunto Ambit3 Ambit 3 Peak Watch-Black by Suunto, £209.00 - £463.10
"Not cheap" indeed!
Terry, East Grinstead, UK