In order to install ("side load") WSL apps from outside the Microsoft store one has to follow several steps
- make sure side loading is enabled
- download the appx
- install the signing certificate
- run the appx file
Allow side loading
Go to Settings -> Update&Security -> For developers and make sure side loading is permitted:
Download the appx file
Windows Apps are actually zip files with special meta data in it. The file suffix is "appx". Currently in development appx files for openSUSE are available from download.opensuse.org.
Install the certificate
Apps in the Microsoft Store are signed by a trusted certificate. Side loaded apps are signed by a developer certificate. In case of openSUSE that certificate is stored in the openSUSE build service. Conveniently the appx file has the certificate embedded, so right clicking on the appx file and following some steps allows to import the certificate as trusted:
Launch the appx
Just double click on the appx to make it run.
or from PowerShell: