TV device wall mounting on wood stud wall - How to mount?

The entire house actually consists of normal chipboard panels. OSB was not installed anywhere (only retroactively by us in the bathroom). The house was built in 1979, back then there was no such thing as OSB and there is no installation level either.

I already had the idea to attach a board (OSB if you will) to the wall and reinforce it at that spot. I would then attach the bracket to this board.
With this intermediate layer, I can then use thicker and longer screws.

Another option was to use two beams instead of the board. Then I could use really hefty screws, but aesthetically that wouldn’t be a winner (although, if you paint them white...).

However, I think the exterior wall is out of the question. I can’t imagine not damaging the membrane in the process...

Spax screw into the wall and done.

It was advertised with us that about 50kg is held per screw because of that.

Take a look at the datasheets to see what a 20mm long screw can hold. A 5x50 holds 50kg – but that is of little use to you in a 19mm panel. Especially since a 50cm cantilever can generate significant tensile forces and not just shear forces. Moreover, the drywall in front is not exactly conducive to shear forces.

I already had the idea to attach a board (for example OSB) to the wall and thereby reinforce that spot. I would then attach the bracket to this board. With this intermediate layer, I can use thicker and longer screws.
..

Why would a board hold better on the wall than the bracket without a board?

What is against the Fischer KD4?

Why should a board hold better on the wall than the bracket without a board?

You can screw in many more screws this way to attach the board to the wall. And also longer ones. I hope for increased load capacity as a result - but of course, I might be completely wrong with this thought.

What is against the Fischer KD4?

I didn't know that one at all, but it looks promising.

70 and 19mm as a substructure are sufficient.

To bring the TV completely into the corner, place an aluminum pipe, 70mm x the desired length, on the wall mount, that is, a pipe like the one used for satellite dishes. This shifts the shear force from the hanging point into both corners along the entire length down to the floor. The pipe can be fastened with pipe clamps for water pipes. The set screw may then - for aesthetic reasons - protrude a maximum of 15mm from the wall because the pipe must lie almost flush against the corner. If you attach the TV wall mount to the pipe with the same pipe clamps, the wall mount is also more height adjustable!