USB-C PD is one thing already, but another issue in your case is the power bank. *These* are the real minefield here. Many only comply with PD marginally, and one of the most annoying things with these is that they are almost all made to go to a sleep mode when the drawn current goes below a certain threshold (which of course depends on each vendor/model), and will not wake up unless you actually disconnect the cable and reconnect it.
Really, while the "power bank" thing looks like a good idea on the surface, it's a nightmare waiting to happen if you're going to design a product around one. These are not made for that use case. There are mainly designed for recharging mobile devices. You're in for a lot of... fun, believe me.