Is there a way to launch a Windows store app from a button ?
Haven't tried it but a quick google showed this: https://www.tenforums.com/software-apps/57000-method-open-any-windows-10-apps-command-line.html
It will depend on the app. Some of them have normal .exe files, although Microsoft inexplicably permission the WindowsApps folder, which UWP apps tend to be stored in, in a way to make it hard for you to find them.
For those, the same thing will apply to running UWP apps from a Command Prompt. Ask the app authors how to do that, and the answer they give will also apply to running their apps via Opus buttons.
Others can be launched via the FileType command with ACTION=shellex on a file the app can handle, possibly using the SHELLCLASS argument to specify the class name the UWP app is registered under (usually an obfuscated string, another inexplicable choice by Microsoft when designing UWP/Metro/etc.).
A bigger question is why you would ever want to run a UWP app. 
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Here's an example
lol. just wanted windows photo viewer on a button. I will put it as default so it runs from the 'open' in right click menu and still have dopus viewer as primary.
This will open the selected file in the Windows 10 Photos app:
FileType ACTION=shellex SHELLCLASS=AppX43hnxtbyyps62jhe9sqpdzxn1790zetc
(The AppX43hnxtbyyps62jhe9sqpdzxn1790zetc part is Microsoft's fault. 
Normal apps have human readable names but UWP ones are like that.)
thankyou.
Maybe the developer wanted to use a much easier name, but accidently pasted his very secure password into the registry key?
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