My condolences on your loss

Sounds like that was one scary situation.
I just wanted to chime in with SignOfZeta and say that probably most of those systems (and games) should be usable with some cleaning. Just dismantle any of the systems and run them through a dish washer with a mild dish soap. Let them dry for 2 days to make certain they're fully dry, then reassemble. It would be a LOT of work, but you should be ready to rock after that

Hucards should clean off easily too...maybe put them all in a load of the dish washer as well... Never tried that, but I can't see how it could hurt them.
Fortunately, as long as electronics aren't running at the time, they can get wet or muddy and it won't ruin them.
Good luck with the clean up, and glad you made it out safely!
RG