The ThinkPad T14 series is among the most well known and liked business laptop series. It is not a premium series, but it delivers a well-rounded combination of quality and features. With the lastest Intel Lunar Lake CPU, it is more efficient than ever, setting a new battery life record for the T14 series.
A comparison of Lenovo Thinkpad t14 over the years and how the new lunar lake cpu stacks up.
I carry a ~300 Wh power bank with my laptop.
https://www.amazon.com/dp/B0D62PMB3R
They also have a less-elaborate, smaller, lighter, less-expensive ~200 Wh model that’s probably more actually-practical:
https://www.amazon.com/Anker-Portable-Generator-Traveling-Emergencies/dp/B0D62P85ZR
Note that you can’t take anything over 100 Wh on a flight in the US. I also have a 100 Wh power bank that I keep around for flights.