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.
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.
Nubia has been sharing teasers of the Z60 Ultra for the past couple of days. So far, the brand has shared glimpses of the design, some screen specs, and the smartphone's official launch date. Now, it has revealed key info about the device's wide-angle camera.