great news.
RICOH recommends the official RICOH cable, but I do not know where to buy them from.
I tested the Ankder USB C Cable. It worked in my tests. Keep in mind that I don’t work for RICOH, so this is not official information. Get the shortest length that will work for your charging setup. I know other people that are using the same cable.
RICOH lists powerbanks on their site, the FAQ portion.
https://topics.theta360.com/en/faq/c_00_z1/35/
Make sure the powerbank can deliver over 1amp, (1000 mA).
In my personal tests, the Z1 doesn’t draw more than 1 Amp.
If the powerbank can only output a max of 500 mAmps, it may not be enough.
Portable battery chargers on RICOH FAQ site for Z1.