After filtering the reviews, I bought the camera with mixed feelings.
For the price the device is usable.
The app was initialized in 2 minutes.

The image quality can be described as pretty good when the camera head is stationary.
From 3 cm, a sharp image is obtained up to several meters - but only under external lighting.
When the camera lighting is fully turned up, it ends at around 10 cm, depending on the brightness of the object;
With additional lighting, visibility can be significantly extended.
In fact, the device becomes alarmingly hot after a few minutes of use.

The rigid cable in connection with the basic device is very cumbersome, and in fact exists
The danger of the cable entry breaking out quickly...
I attached the device and the 10 cm cable with cable ties to a heavy metal strip (cooling) so that you can get started without worrying - you just put the part somewhere.

The rigid cable is the compromise in order to get somewhere better and more targeted - I rolled it up into approx. 40 cm rings, which makes it easier to handle and put down later.
The option in the app to rotate the image by 90 degrees is very valuable, so you have better control of the orientation.
The video quality is only usable when the movement is very slow.

Conclusion:
Inexpensive device for particularly tricky applications