Bill Claff has posted the full Sony A1 dynamic range and read noise charts at Photons to Photos. I immediately took a look at the A1 vs. A7R3 as can be seen here:
I think most shooters will be satisfied, at base ISO there nearly a half stop advantage of the A9II and only 1/3 stop deficit vs. the A7R3. As the ISO rises to 640 and above the cameras all equal out.
Interestingly, Bill notes that the dual gain conversion happens at ISO 500 for the A1 vs. ISO 640 for the A7R3/A7III/A9II.
For read noise, there isn't a consistent trend, but generally the A7R3 is better at the lower ISOs and the A9II is better at the high end. However, I don't know about about read noise ratings to say if any of the differences will be significant or visible in most shots.
