Awesome, this might be just what I needed! I need to run vscode and it seems to be possible if you launch it with --enable-features=UseOzonePlatform --ozone-platform=wayland . I'll play around with it the next days, thanks!
RDP as a protocol does support remoting just apps (RAIL: Remote Application Integrated Locally, or RemoteApps).
However, for Wayland compositors, this is a distant future; right now, Mutter supports connecting to existing, already running session (desktop). Ability create a new session over RDP is in the works. Everything else is after that.
A lot of time I don't want a remote "desktop", but rather just launch an app and have it sent over an SSH tunnel (-X/-Y).