Going to first of all admit, I'm no expert when it comes to color spaces.
I've been using the ACES SDR transform for a while and that's working pretty well throughout my/our pipeline.

But I'm wondering what's the steps to start working with/creating more dynamic HDR content.
I figured starting in Houdini and setting viewport display space to Rec.2100-PQ and View transform to ACES 1.1 HDR would be a good start, but the viewport/IPR render gets completely washed out and de-saturated compared to the SDR view transform. There's not much information about any of this out there, so just wondering if anyone got some pointers?

I did try download the ACES OCIO v2.4 config and use that, but it didn't seem to make any difference either.
Windows and the monitor is running with HDR enabled, and the monitor is set to its HDR PQ_BT.2020 preset.

Just bumping an old thread, I'm in the same boat.

It seems like we want the inverse of this transform, or at least maybe we need to tell our OS that Houdini viewport is HDR content somehow. Right now it looks like its just transforming SDR into SDR again using an HDR function.

HDR in the viewer is only supported on Mac OS

Log spaces like PQ still don't display as HDR on Mac, however it's not required. Simply select Display P3 - Display as the display and Untonemapped as the view and you will get HDR values without tone mapping. to get The ACES 1.1 HDR 1000 nits tone map applied, edit the config by adding the ACES 1.1 view to the Display P3 display and it will tone map it with HDR head room.