I know nothing of shop operations in the time of Covid but any time we were confronted with a risky prospect we'd ask for a substantial deposit for the work, at least enough to cover the cost of the parts in case the customer never showed again. I'd hate to think that such a sound practice is now extinct.
The OP could always look for another used bike with a similar rear wheel and buy it to cannibalize. It would have to be a Shimano hub with the proper-sized rim and in better shape then the one he has, but it might be a while before one of those showed up. Worth a look.
@
sweeks had a good idea about replacing just a few spokes and learning to true and @
ericoseveins is emerging as the real hero offering to help you. Buy that man a beer, or however many he can consume during a wheel build.