I think we should stop this conversation about headphones and instead talk about walking for 10 hours in the Scottish mountains.. that’s so cool!
If you are interested I can recommend:
https://www.walkhighlands.co.uk/
And I've been watching these videos to stay (relatively) sane these last few weeks:
Well, I listen to audiobooks while walking in the Scottish mountains and 10+ hour days are possible and when running multiple apps (OS maps, Endomondo, Audible) I do need to charge and use my phone at the same time (I have a dual lightning/headphone adapter that supports charging and listening at the same time).