Can restlet perform generate invoice pdf, using the standard invoice advanced pdf template, and pass to externally called website link (using shopify webstore)?

You could use the template to render the record and store it in the filecabinet which, because it's a file in the file cabinet has a URL if that's what you 're after? Might just need to check if n/render is available in a RESTlet.

I want to share that pdf file over to the webstore, or display on webpage and avoid taking up filecabinet space.

restlets are inconvenient for binary responses since they use plaintext output