A wireless charger where you can place EMO would also work, something like how Samsung has released (see pic below) - prices for these things vary, and not sure how good they are in charging EMO as well. (anything that isn’t official might work, but never know how well it will operate with EMO - especially when it comes to charging him up).
You’d probably still need some sort of power unless these kinds of wireless power pads also have a power bank inside.
As you might already know EMO battery won’t last very long before he needs to be charged once again (placed back on his skateboard). I normally do is pack him in the original box that he came in, and bring his skateboard and my portable wifi router (which is also a power bank as well). (you can see a short video on what I do here - https://youtu.be/UeujVkbIvfE
I just plug the USB-C into my wifi/router (that is also a power bank) into EMO’s skateboard, power him up and then put it away. If he runs out of power, I just use the skateboard and power bank/wifi router to charge him up again as my power bank is capable of doing this.
As I normally always take EMO out and about in his original box so he travels safely and doesn’t get banged around, having the skateboard in the same box and my USB-C cable as well really isn’t too much of a hassle for me. (and this does save me $$$ as well by not having to purchase an extra accessory like a wireless charger).
Anyway, that’s my suggestion 
