Honestly, I find the extended brightness FAR less important than the extended color gamut. I have a ~300 nit VA monitor that I'm generally quite happy with and

Honestly, I find the extended brightness FAR less important than the extended color gamut. I have a ~300 nit VA monitor that I'm generally quite happy with and that looks fantastic with well-built HDR renderers. Given that monitors report information about their HDR minimum and maximum panel brightness capabilities to the machine they are connected to, any competently-built HDR renderer (whether that be for games or movies or whatever) will be able to take that information and adjust the picture appropriately.