After a brief search I can't find any mention of any punishment for Sisyphus if he stopped pushing the boulder up the hill. That said, this is all taking place in Tartarus so there probably isn't much else to do and endlessly push a boulder up hill might be the better option lol. I can relate.
I agree, the delivery services are definitely price gouging to a degree. It sucks that we're charged for delivery, service fees AND the item prices are inflated by around 20% too. Thing is, I think there's a bunch of reasons that TonyDelivers will eventually become as bad as the current market leaders. As his company grows, takes on employees, builds infrastructure, overheads increase, management grows - they'll fall into the same "traps"/profit seeking the other delivery companies have fallen into.