Iolva
I spent about 8 hours on this and finally did it! (at least on android)
Add Browser -> Execute Javascript "window.plugins.socialsharing.share('Your message you want to share');"
action to the project. Export it for Cordova with min SDK=5.0
Then I followed this great tutorial. On page 3 before executing "cordova prepare" command you need to run
cordova plugin add cordova-plugin-x-socialsharing
This will add the social sharing plugin to the project.
Use "cordova build android", upload apk to the phone and run.
Alternatively you can use Construct 3 service to build the app, but you still need to add the plugin first.