Is there any way to miminize DO Light to a tray icon - or, for that matter, to display a tray icon for DO Light? I'm using Win 10, 64 bit.
Not built-in to the Light version, I'm afraid.
The Pro version has an option to add a tray icon with configurable double-click action and right-click menu. (It isn't literally "minimise to tray" but can work similarly if you close a window and set the tray icon to re-open the last closed window.)
With the Light version, we envisage Opus being launched and exited as is needed like a normal app, and which is easier to understand.
With the Pro version, although it can be configured to work the same as Light and exit when not in use, we envisage it as more of an always-available resident tool, always ready in the background and waiting to be triggered via more methods (double-clicking the desktop wallpaper, global hotkeys, tray icon, launching folders in other programs, etc.).