The plastic bracket that attaches to the Switch and holds the power bank on is very low profile, so it can be left on the switch. I have a form fitting hard zip case and the Switch fits in there with the bracket on. You have to take the battery off first of course, as it won't fit in most cases with it on. Luckily the battery slides on and off very easily, but it's not loose or wobbly when attached.
The battery does add some weight to the switch, but what can you expect. The kickstand is covered by the power bank. The bottom has the USB C plug sticking out anyway, so even if the kickstand was to work, the Switch wouldn't sit flat.
I tried the power bank on my Switch Lite, but the bracket is too big since it's made for the original switch. It still works fine on the Lite, just not attached like on my regular Switch. It comes with a short USB A to USB C cable to charge the power bank and has the built is USB C out for the Switch, so all you need is a wall plug with a USB A output to charge the power bank.
Don't have anything negative to say since it's exactly as specified. It's really the best power bank for the Switch right now in my opinion. Even the Nintendo branded official power bank doesn't attach to the Switch or have a built in USB C cable.