The main difference with the commercial solutions is the lack of a photocam, that downs allow to read QR.
Sorry, this part of your post confused me a bit. Are you saying that the DIY Jade when purchased disassembled doesn't come with a camera or that it does but the camera is of bad quality? If it's the latter, then I can confirm that. More precisely, it's not that the camera sucks to a degree of being useless, it's the software companion apps like Sparrow Wallet that can't scan the QR codes as well as they should. Another user also said that they were struggling with their Sparrow-Jade combo.
Are you using the Jade as a stateless signer and with what companion app?