I have a 1½-year-old laptop AMD Ryzen 6860Z processor & get 9 hours on the regular running NixOS doing programming/browsing/chat. That’s not quite 8 hours with 30% to spare, but good enough that I don’t worry about carrying my charger (but being lightweight GaN, normally keep it in my bag just in case). Apple folks have this tendency to think all their hardware is massively better, but even if it’s ‘better’, it’s often just by a small margin that doesn’t make a big difference–especially when you factor in cost.
demonsword