I've been working on a tool that would make it easy for webdevelopers to see which layout features are in the font, to which characters they apply, and what CSS you'd need to enable them on the web. The generated CSS cascades and can be combined by applying a class per layout feature, something that's usually hard to do due to font-feature-settings not cascading and the lack of support for font-variant-*.
You can try the tool here: https://wakamaifondue.com/
Note that fonts aren't being uploaded to a server—everything is processed locally in your browser.
If you see things that can be improved, I'd appreciate the feedback!