Headlamps for sensitive applications will ALWAYS involve a replaceable or external battery. Can't have your light going out when you are in a dangerous situation. When I used to rock climb, I always kept 3x AAA's taped to the strap in case the one I had in died. Never needed to use them, but made me much more confortable.
A lithium ion headlamp plus power bank does the same thing for the same weight and more flexibility. You can also charge phone, InReach, cameras. You can decide what is most important use of power. That’s the standard these days.
Another approach is to bring 2 charged headlamps. Again, same weight as an old headlamp + 3AAAs. But covers additional failures like breaking or dropping.
