How to pull files from almost bricked android device? (Common suggestions didn't work)
So. The question was basically whether it is possible to write a new build.prop to enable usb debugging when no original template is available.

The answer is yes.

I found out that the stock recovery of the tablet is able to show the latest log files, and these logs contain all entries of the build.prop. Or perhaps the default.prop. After I was able to get a rom image of the stock firmware and was able to unpack this, I had a genuine build.prop to compare.

However, this (new) build.prop with enabled usb debugging was not solving my problem with accessing the photos of the bricked tablet. I was in fact able to push this build.prop into /system folder, but without any effect. But that is subject of another question / thread.