Hello,
everything started with one problem - the stock camera app froze right after start and even though OpenCamera did show the camera input, it was not able to focus. My idea was that the problem is in the software, so I backed up everything valuable, than loaded LineageOS.
As you probably guess, the problem was still there. I believe that fingerprint sensor did work at this stage before first opening correctly. So I opened the phone, having no clue, what to do. But Heureka! I found one of the camera connector completely disconnected. So I connected it back and the camera started