You are correct, Reflow and Ecwid work in totally different ways. But once you get used to the way Reflow works, it will all fall I place. 
It will take some getting used to.
I was revisiting your demo and could not figure out what was supposed to happen when you clicked on the CART icon in the menu bar.
I expected it to either take me to a floating cart or possibly a cart page, but nothing happens.
Which framework demo?
Foundry 3.
If you’d like me to look at your project, please DM it to me.
Here is the test project. I could not figure out how to send it any other way.
(Attachment Reflow-Test.rwc.zip is missing)
How do I DM it too you?
Use the email option in your profile