Exporting all frames in EXR Untonemapped 32bit should retain all render information, but i'm not sure how to change the color space to REC 2020, since the primaries of sRGB-Rec 709 and REC 2020 are different. I've done some testing changing the tonemap , and it seems the primaries and color gamut are allways sRGB-Rec 709.
Is it possible to change the color space and use a wider color gamut natively such as Rec 2020 (HLG or PQ)?
Here there is a link talking about ORBX that embrace Rec 2020 viewtopic.php?f=7&t=41609
https://en.wikipedia.org/wiki/Rec._2020