Quickly copy selected vector or raster layer path into clipboad (Ctrl+Shift+C) and paste layer (Ctrl+Shift+V) into same or other instance of QGIS including current style
Important: It is needed to change/set none default "Ctrl+Shift+C" and "Ctrl+Shift+V" shortcuts in "Settings/Configure shortcuts..."
Ctrl+Shift+V - Add Vector Layer
Ctrl+Shift+C - Set CRS of Layer(s)
Or assign there your custom shortcuts to "Copy layer path" and "Load layer by path"