[doix]

A lot of airlines do have max weight limits on hand luggage, around 8-10kg. They almost never check, but I did get caught out once.

I travel with a laptop, portable monitor, iPad pro, switch, GoPro, moonlander keyboard, mouse, bunch of plug adapters and a multiway extension. All of that adds up to 9kg when you include the bag base weight.

One time when I was flying from Istanbul to Mauritius, they weighed the bag and it was a big headache. Eventually someone else came along and just let me on since it was all battery powered stuff that couldn't go in the hold.

Charging by weight doesn't make more room in the overhead storage though. Going by volume does, and many airlines do check volume. Especially in Europe, I've seen Ryanair and easyJet stop people many times.

If you look on Amazon, you'll see entire ranges of bags optimized for Ryanair free carry-on limits.