With my N900 I used to travel with 6 to 10 charged batteries to have a few days of runtime. Things got better now with powerbanks - but for something like hiking just carrying a few spares would still be smaller and lighter.
Honestly for hiking I’d suggest a power bank with solar charge capability. One thing to charge them all.
The space used by the smallest solar charger I’ve seen on Amazon seems to be similar to 6 or more batteries in the format the N900 was taking - so if you look at space, slow charging from solar charger, and reliance on sun conditions taking individual batteries seems to be the better option for a few days hike. It’s also easier to stow individual batteries to wherever you still have space left.