Well, generally, pinch at the top doesn't mean much to me. I generally am able to take a piston/sleeve/connecting rod out of the engine, put my thumb over the top of the sleeve. Push the piston into the sleeve and when the piston closes the ports, I can feel resistance in the form of pressure. Now, that's not scientific because air will leak out because of the contour of my thumb, but, I feel air should only come out from the top. Not from the sides of the piston. Also, I should at least have some sign of compression.

All engine should seal with some form of compression otherwise, how is the engine able to make power??

Given the engine rotates as such a fast RPM, the compression is brief, but, I think there should be something there.

I also feel when the engine is turned over to TDC, you should not be able to turn the crank where there is a clicking noise which due to the slop in the base of the rod. If this much slop exists, when you run the engine, this pounding will quickly kill the rod and possibly the p/sleeve.