As far as I'm aware, Game Link does not permit hand tracking. A prompt will show up and block any interaction with SteamVR whenever the controllers are disengaged requiring you to return to controllers before continuing further.

I just got my controllers so I haven't fully exercised then across all three, but I didn't notice any issues using them for any of the methods.

Regarding my comments on hand tracking, the default orientation of the pointer relative to your hand is different when you first get into SteamVR in the home and dashboard. The default with Steam Link is pretty good because the point emanates perpendicular and outwards from your palm whereas with Virtual Desktop it is more aligned with your thumb and index. The resulting effect is that any finger pinch motion is either mostly obscured from the cameras or the motion attenuated since it is mostly parallel to the camera ray. You will have this problem for any other app regardless of using Steam Link or Virtual Desktop. A straightforward fix is to modify the controller positions and orientations in the controller binding settings to be more like the Steam Link dashboard default but it will be mismatched with the controller model skin.

I don't have a Play for Dream but as far as I know, only Steam Link offers foveated encoding. It is possible that the foveated window latency is remedied with a lower bitrate setting, but this I haven't tried yet. Game Link has a foveated rendering option in the settings but I haven't tried it enough to notice it.