The SR1 files that I’ve seen at base ISO are fab but past that not usable, plus camera at this point is reported to have serious bugs.
FF sensors never have and never will surpass MF IQ on an iPad they look the same, but in print no comparison.
H system is designed primarily for shooting with Phocus and gives superior in camera results with perfect color, no noise, best DR and little PP needed except for personal style.
Mixed reports on X1D & 50 r/s depending on how it’s being used and for what which leads me to my point. If a future FF completely fills your needs then at those prices two bodies with a collection of some excellent glass of you choice has been available for at least two years. Nothing that has been released since 2017 has changed that stage.
Finally any sensor from Sony or Towerjazz or... is worthless without the coding tying the sensor to not only the body and lens but incamera PP of the RAW data.