Whilst I migrated from Linux to Windows and WSL 2 more than a year ago, I had a plan to install any development-related tools like Git or PHPStorm in WSL2. PHPStorm worked quite ok in WSL 2 except that filesystem changes (e.g. adding or removing files) made directly in WSL 2 were not properly recognized by PHPStorm. Even triggering a manual refresh from the disk did not always work. That made me install PHPStorm on Windows and open PHP projects via the WSL 2 integration of PHPStorm. That works better but still has its issues with larger projects.
Current situation: I have no local webserver running and just php5-cli (plus a few extensions) installed as most of the development I do will make use of a Vagrant machine. From time to time I develop small tools or libs which I like to debug on the command line. This is an overview how I configured my Ubuntu 14.04 box to handle debugging with Xdebug and phpstorm.