Yes, as long as the battery pack can be connected with USB-C cable.

Hello,
I got myself a power bank. If you run the Beoplay A1 at full volume, it will run out of juice after about 5 hours. In my opinion, a power bank with 10,000 mAh is enough.
I found a site where you can find many test reports, including the A1.
https://www.blauer-zahn.de
There you can also find tips and tricks on how to pair 2 devices via the app.
LG