[scarface74]

My work MacBook Pro will already last two workdays of normal use on a full charge when I am at a customer’s site in meetings, taking notes, doing PowerPoint presentations, etc.

I then carry this around that got me through a third day (Amazon. Not an affiliate link.)

Anker 747 Power Bank (PowerCore 26K for Laptop), 87W Max Output with 65W USB-C Charger, https://a.co/d/52vd8Ec

This is the largest battery allowed on an Airplane.

[Grimburger]

I really wish they would allow larger. I have a K2 and it's perfect for extended periods without messing around with powerpoints