Best cheap cameras for low fps 4K over wifi

I’m looking for cheap 4K cameras to use with double-take and compreface. I’ve already got 6 surveillance cameras around my house, but the resolution doesn’t work well with facial recognition unless you’re really close to the camera.

Are there are options for really cheap low fps 4K cameras like an ESP CAM or a raspi cam combo or something off the shelf that I can integrate into my wifi or zigbee network that I can use solely for facial recognition?