Goal: a completely headless Linux box that presents a virtual display and streams 4K 120Hz HDR to a Mac/iPad over Sunshine → Moonlight, with nothing physically plugged into the GPU. This is a running log of how far that gets on current NVIDIA + KDE Wayland, what works, and exactly where it hits a wall.
TL;DR: HDR works. 4K60 works. Arbitrary native resolutions work. 120Hz does not — the NVIDIA driver refuses to bring up HDMI 2.1 FRL (or DP DSC) on a force-enabled connector that has no real sink doing the link handshake, so anything needing more than ~600 MHz TMDS