looks like you have everything you need here:
https://forum.corona-renderer.com/index.php?topic=40952.msg216985#msg216985you are good to go with luts I posted a while ago.
edit: no need for string options or gamma operators in vfb.
in Corona Image Editor / VFB:
LUT: mP_Corona_AgX_A_matrix.cube (this is color matrix from AgX ocio config simulated as lut for Corona and Corona only, it relies on how Corona handles luts, will not work as expected anywhere else - use ocio instead)
LUT(logarythmic): mP_Corona_AgX_B_log_AgX_kraken.cube (this take us to AgX Log (Kraken) - make all your colour correction, grading, look or whatever here)
here goes your custom look, lut most likely. create it on AgX Log (Kraken) image saved from CIE or frame buffer. in Fusion, Photoshop etc.
LUT: AgX_Default_Contrast.cube (attached below, this one would put your Kraken log nicely on a srgb display. edit: nicely but still missing the "look" so it is "bland" on purpose. this is cube version on the lut from original AgX ocio. 1D lut, just a contrast curve. you can obviously add this transform to your look for convenience)
and if you find AgX great - do not forget to say
Thank You to Troy Sobotka:
https://blenderartists.org/t/dealing-with-aces-agx-srgb/1480752/662