Out of habit from using Ubuntu, to focus Google Chrome I hit the Start Menu button and type "ch" (which autocompletes to Chrome) and hit enter to open Chrome. This is faster than using Alt+Tab and using mental energy trying to find Chrome window. However in Windows 10 this always opens a new window and I'm left with a bunch of windows open and a cluttered desktop.
To mimic the behaviour of opening Google Chrome from macOS's Spotlight or Ubuntu's start menu where if you already have a Google Chrome instance, it will focus the open window rather than create a new window. Windows 10 by default always open a new Chrome window from the start menu.