Instantly apply Troy Sobotka's AgX transform to your 32-bit (EXR/HDR) renders in Affinity Photo non-destructively.
These macros are intended for HDR documents (OpenEXR, Radiance HDR). When saving to these formats, Blender writes out linear scene-referred values, so you do not get the AgX transform applied.
Applying the AgX transform in Affinity Photo is possible but complicated, and involves installing OpenColorIO configuration files then using a combination of the OCIO and LUT adjustments.
Instead, these macros can be added to a fresh install of Affinity Photo—no other dependencies like OpenColorIO—and you can apply the AgX transform non-destructively.
Free to download, but if you want to donate for time and work it's much appreciated :)
Blender AgX Transform Macros (Affinity Photo)