The Sony A7IV sensor score has been published here: https://www.dxomark.com/sony-a7-iv-sensor-test/ . The key messages :

• With its new 33MPix sensor, it achieves a DXOMARK Sensor score of 97 and tops it predecessor by one point.
• It still shines for landscape use case with its 14.7 EVs maximum dynamic range.
• For the rest, sensor performance remains quite close to A7III, one of the main difference being that the A7IV activates its second read-out mode starting ISO400, providing a dynamic range boost, while the A7III activated it at ISO 800.

The conclusion:

As the 24 MP BSI-CMOS full-frame sensor equips the out-going Sony A7 III, and the majority of Sony’s rivals at this level, the new 33 MP BSI-type CMOS in the Sony A7 IV will also probably appear in forthcoming competitor’s models, so the results are doubly interesting.
While the new sensor doesn’t perform a lot differently from the outgoing device, there has been a useful increase in the overall pixel count of 37.5% (albeit a 16.8% increase in linear pixel count on the long-edge). This may appear somewhat incremental, but when combined with the various improvements in stills and video features, the new Sony A7 IV is an incredibly well-rounded hybrid and a highly attractive option for all sorts of genres.

Sony A7IV:
In the USA at BHphoto . Amazon . Adorama . FocusCamera . BuyDig .
In Europe at Fotokoch DE . Calumet DE . Foto Erhardt DE . Park UK . Wex UK . Amazon DE . Amazon UK . Amazon IT . Amazon ES . Amazon NL .