In my experience, remote desktop solutions that use hardware accelerated encoding (Parsec, Nvidia GameStream, Steam Remote Play) are virtually indistinguishable from a local session when using wired Gigabit Ethernet. Even over the internet, the delay is only really noticeable in fast games. Would be great if RDP or VNC could catch up with this technology.
I'm a contributor for the Sunshine project: https://github.com/SunshineStream/Sunshine project, which allows Nvidia GameStream to be used on Linux systems with Moonlight clients. I haven't tested the Linux side of things, but it has many ways to both encode the screen or acquire it (via KMS, Pipewire or x11grab IIRC).
RDP at least is probably vastly more efficient as it doesn't encode the entire screen as a video every frame. This is what gives it the flexibility to have the remote display resolution and DPI be independent of the local settings, for one. It's actually quite sophisticated, unlike VNC and its ilk, but it isn't optimized for gaming.
Not true anymore. RDP encodes the entire desktop as it is more efficient than relaying the draw commands. You will notice compression artifacts on a poor network connection as RDP reduces the bitrate to compensate.
Gnome-remote-desktop in Gnome 42 (to be released soon) uses NVENC for H.264 encoding, if available. Of course, the client must support that too (many do, if the user left everything at 'auto').
