> Since we do anecdotes here, a friend who is purely heavy lifter (squats, deadlifts, benchpresses etc), exactly in those low reps range, and pretty good at it. He is utterly useless in 2h+ hikes with 1000m+ elevation gains.

Kind of a false equivalence. Firstly, I'm not sure that long, arduous hikes are very relatable to e.g. moving around in old age, whereas doing a single squat is absolutely comparable to getting out of a chair for anyone. Secondly, my guess is that you'd be utterly useless if you had to carry a pack whose weight equalised the difference between your respective bodyweights.