you wanna design a couple of low-power rf beacons that can be directionally tracked out to a 800ft range or so (only half joking)
Requirements: 1x1x3/4ish dimensions, water resistant, 1 month battery life, directional finding
Commercial equivalent products that are awesome when they work, but super shittily made.
and this old ham radio dude that made his own product, that is probably awesome, but costs half a grand
Why not put one of those apple things on your cat lol
Airtag! Airtag your catto