I power my VIM4 with a Pine Power, and found it to to be very sensitive to input from both the 12v source, and the quality/resistance of USB-C cable employed.
The 5v Anker linked will definitely not work. A good resource for choosing a 12v powerbank is linked here:
I decided to try a Green Cell GC PowerPlay20 and did not have any problems so far powering my VIM4: Booting into Ubuntu an Android, doing some web browsing worked well.
The relevant specs from the product page (emphasis added by me):
I am sure other models work as well, but this is now one confirmed option. If I should discover any problems, maybe with heavier workloads, I will update this thread accordingly.