The idea of a "main-level" ultra wide-angle sensor has been already done by Oppo with their Find X6 Pro. What they didn't was having such a bright aperture (f1.8 vs f2.2 on the X6 Pro) and also feature OIS. It will be sure interesting!
As for the main camera I expect it to be the same as the Z50S Pro if they keep the 35mm focal length selling point, especially since their 1-inch 35mm prototype had a monstrous camera hump. The periscope zoom lens smells like a OV64B given the MP count and the fact that it's becoming very popular.
I think the main sensor will be the Sony LYT-800. And you might be right about the periscope camera.
From what I read it would be the same sensor as the Ultrawide. Though you may also be right, they can use the LYT-800, crop the 53MP to 50MP and be the direct sucessor to the IMX800 used in the Z50S Pro.