Someone else suggested the whistle, which looks a plausible off the shelf solution. But otherwise:
Mount a bell on your cat. Maybe more than one, with different sounds - collar, back and (if you can get him to tolerate it) a leg. Then train an ML model to recognise the sound of a seizure.
There are a few options for electronic collar-mounted platforms. But finding one that is all three of capable, lightweight enough for the cat, and has decent battery life, is difficult. We already know that bells are light enough, and they don't have a battery life problem. My guess is that ML will easily be able to detect a seizure with high accuracy, probably even with only one bell. You might need a mic in each room.
(after watching the video) It may even be enough to just detect the bell, and have a crude threshold for the proportion of time it's been ringing in the last minute or so - which will be a lot faster to gather the data for. That would be a good MVP.
Mount a bell on your cat. Maybe more than one, with different sounds - collar, back and (if you can get him to tolerate it) a leg. Then train an ML model to recognise the sound of a seizure.
There are a few options for electronic collar-mounted platforms. But finding one that is all three of capable, lightweight enough for the cat, and has decent battery life, is difficult. We already know that bells are light enough, and they don't have a battery life problem. My guess is that ML will easily be able to detect a seizure with high accuracy, probably even with only one bell. You might need a mic in each room.
(after watching the video) It may even be enough to just detect the bell, and have a crude threshold for the proportion of time it's been ringing in the last minute or so - which will be a lot faster to gather the data for. That would be a good MVP.