I can only speak about my plugin. It doesn't sound quite as fancy as the one above but it was written for a specific brief so...
The idea is that you create products in WooCommerce on Wordpress and you create matching courses in Moodle. They are linked by the 'SKU' code in WooCommerce to the Course short name in Moodle.
The customer can then buy and pay for their courses in WooCommerce/Wordpress. The front page of Wordpress (or any place you want to put it) has a button saying "Go to my courses". This takes you to Moodle, creates your profile and enrols you on your courses.
If you log into Moodle directly, it "phone's home" to Wordpress to authenticate you and fetch your latest enrolments.
Currently we are only providing this as an add-on service for our hosting packages but it may well be contributed as a plug in some time in the future,