Small tangent, I didn’t have the energy to read your whole post, so you might have addressed that. But often it’s cheaper to go with an established multi purpose device instead of building something new.
I used to build and sell Raspberry Pi gaming handhelds that were as cheap as possible and literally just held together by some string. My purpose was to get enough money through the sales to be able to build one for myself. Sure, the building process was fun. But when I crunched the numbers just buying a cheap smartphone and controller was much cheaper and more performant and versatile than the self-built solution.
Just buying a cheap phone or tablet is often the cheaper solution.
Heck, even Valve just bought off the shelve tablet displays and turned the image in software for the Steam Deck.
A few years ago I saw someone just simply checking for a cat head silhouette. Was enough to deter other animals and also worked to recognise if the cat had caught something.
We have a cat flap that detects the RFID chip in her shoulder. It seems to be broken since a few weeks. But our cat (and not the stupid neighbour’s cat) can open it anyways with a little prying with her claw. But luckily that doesn’t work as well when she has an animal in her mouth. So we will probably leave it broken.