You can try looking into a sleep position trainer. It isn’t what you’re asking about, but it has had good results in reducing or eliminating the paralysis episodes, so it’s a similar outcome.

The problem with what you’re specifically asking about is that nobody has gone into production afaik. There’s patents for things like they, but they’re either junk (and obviously so), or would be way too complicated to set up and use reliably. Sleep paralysis isn’t usually responsive to just shaking by itself.

But you could try something similar to the alarms made for deaf people, if you have a consistent timing with your episodes. Or do something like strap a massager to your hand where you can cut it on and hope that the vibration breaks through. People have made that work, though it isn’t consistent afaik.