I’ve had several Eve door sensors for years, starting back when they were thread +HomeKit. I’ve updated them to matter and have them in HomeKit and home assistant. They are always reliable. Battery is harder to find off the shelf, but I recently found some rechargeables, so we’ll see how that goes. It is bulky like you say. The aesthetics still bug me a bit.
I looked at the Aqara p2 when I recently bought another Eve sensor. Ultimately just looked bulky in a different way to me, so didn’t find a reason to switch since I already had so many Eve. The Aqara Zigbee sensor seems more like the right size to me. I don’t know why the thread versions have to be bigger. Seemed fine though as far as I could tell.
I think the onvis ct3 is thread + HomeKit. I don’t think it supports matter?