Pixel shift mode is quite useless and gimmick because of the diffraction limit. It only decrease the sharpness if the resolution goes beyond the diffraction limit. With GFX100S, the diffraction limit on 400mp was F/4 and FF’s diffraction limit on 200mp was also F/4. Camera brands never talked about this instead of only advertising the pros.
I wouldn’t use pixel shift mode unless you need 100% RGB channel but even then, it’s not a big deal.