So there has been support for developing in HTML5/JS since I believe Flash CS6, and also in the various iterations of Adobe Flash CC. Is there a big difference between using the canvas tools in these older versions of Flash versus using them in the newer Adobe Animate? What canvas work can you do in the new versions that you couldn't do in the older Flash-branded programs?
With any recent version of CC there are custom FLA types, and so the FLA itself knows that it's HTML5 Canvas. You can code without comments, you get auto complete as you type code. There's a Components panel for HTML5 Canvas objects. A lot of work was put into the HTML templates, and so you can publish pages that will scale the content. Use of sprite sheets was added to reduce the number of files that had to download.
If you could somehow replicate the HTML, and you could code without needing any code hinting, it ought to be possible to get the same end results. It would just be harder to get there.