Depends, If you want @jcpb s feature set it could get somewhat complicated but if you just wanted a basic 100/65w power bank you could straight up hook up an off the shelve powerbank board up to the battery, It allready has it’s built in bms so don’t need that. Getting absic powerbank functionality would be as easy as hooking it up to something like an ip2368 board and putting a case around it. A cusom board with the battery connector on there would of course be a bit nicter though. I am personally more fond of the ip5389 based boards but I have not found one that doesn’t come with a built in bms and that would probably not work because you don’t get access to the individual cells.
If you want pass-through charging or ups mode it’s going to get quite a bit more complicated.