The most logical first show is Epcot Forever. It’s a huge lagoon, and at the park opened the latest. The only con is the rush on transport after the show. Short of a wall of CMs preventing a mass rush, I think that could be blunted by either keeping select attractions open after the show, or offering a dinner package with prime guaranteed seats followed by dinner after the show. Of course that would mean running transportation later or having the show earlier but I think it could work.
The other show that would be easy (and pretty cheap) to bring back is OUAT, especially if they did multiple shows. That show tends to not draw huge crowds and having multiple shows a night would help even more. A more expensive option that would also be welcome would be Mickey’s Merriest that would accomplish the same thing.
There’s a lot of things Disney could do, even in a pandemic but isn’t. It’s extremely disappointing, and even if the pandemic cooled down or I got a vaccine, I’m not coming back until they start doing something.