Best way to add metadata?

I have made a font with many character variations. For each cv.xx I want to assign a few values from 0-10 to be read by a webb application.

I would also like to be able to “tag” individual glyphs.

Is it possible for me to add more input fields within Glyphs App, so those parameters go into the OpenType font?

I’m not sure what you mean by ‘tags’. You can add UI labels for cvXX features:

Thanks, that looks promising. Is it possible to add the UI labels from within Glyphs App?

Add it to the cvXX feature code.