Not counting the Visa thing like Shmoo described, it would not be hard at all to get around the PVSA. It is written into the PVSA that you can simply pay a $762 fine per passenger for not abiding by the Act. I would be willing to let
DCL tack on an extra $762 pp to my cruise price if they would let us start cruising again. If others think that amount is to high, then they can simply wait until foreign ports come back into service and prices go back to normal. Also, the Act says ships can request waivers during times of National Defense. It would not be hard to articulate that Covid has caused a state of emergency and that not visiting foreign ports would be in the best interest of national defense due to the potential risk of bringing back Covid contracted at those foreign ports. Wouldn't hurt to request such a waiver, the worst that could happen is they say no and you are just right back where you started, no harm.
The easiest way to me would just be to pay the fine or pay the extra cost of the Visas like Schmoo described and then pass those extra Visa costs onto the price of the cruise. I would be understanding that things cost more to get done when your dealing with these draconian regulations from the 1880's.