From my understanding it varies from airline to airline.
I’m looking at the Air Canada page that has details for example which can be found here.
But I’m not sure certain what it means.
Can I have a portable power bank that’s 160W? If I bring that could I also bring on a laptop and a Steam Deck?
It seems like you can bring 15 devices theoretically.
You can’t have power banks in your checked luggage, has to be in your carry on or personal item. They don’t handle the depressurized cargo area very well I assume.