Placing your Snippet on a Wix site

Wix themselves say that you can insert javascript BUT they keep it inside their own HTML frame 
https://support.wix.com/en/article/adding-html-code

So we can't, obviously, create a bar that spans the page as everything is restricted to a Wix frame - It is done on purpose by Wix. 

This is a commercial decision by Wix.  They only allow apps that are approved and in their store (basically they charge for them and take a cut).

You CAN place our bars on your Wix pages using using the 3rd Party Overlay - now called S.M O T. - and overlaying your own pages with the bar