Font Library: include a system fonts collection by default.

[matiasbenedetto]

What?

Is there a chance to include a selection of operating system font stacks like suggested here? WordPress/twentytwentyfour#175
https://github.com/system-fonts/modern-font-stacks
Not be confused with web safe fonts or the usual default serif and sans stacks, here they are grouped by typeface category based on what users have typically installed on their systems using one of the operating systems. OS ship quite a lot of fonts these days and these stacks take advantage of that by categorizing them.

⬆️ Originally suggested by @Ren2049 in this #54169 (comment)

I think we could have a new tab in the Font Library modal featuring these fonts. It would be useful and super-quick to implement due to the Font Library collection API.

Why?

To provide users with a collection of fonts ready to be 'installed' that require no font assets downloads.

Question?

Should we make this part of core or it should be added by a plugin?

[jasmussen]

Good issue, and I'd like a series of stacks like that available, either optionally or by default in the font picker.

However I would suggest this features should not be part of the first version of the library, and in fact it should have a separate interface. I like to think of the font library as a "silo of fonts", similar to how the media library is a silo of images, video, etc. Conceptually thinking of it in that way provides some opportunities to focus and simplify the interface, make it dedicated to font management in a way that might not be as focused if we also add other font settings or configuration. To that end, my instincts would be to have a separate interface for managing font stacks, that isn't part of the "library", but perhaps lives in Global Styles instead.

We might actually discover there that the modal could be the place for it after all, but it needs some visual exploration first, which is another argument here to move a bit slowly.

[LittleBigThing]

For what it's worth, I did test implementing modern font stacks making font stacks available by default, next to the fonts provided by the active theme. The plugin does not work with child themes for now, it's just an idea that could indeed fit in the concept of the Font Library (or indeed 'next to' the possibilities the library provides).

I think providing such stacks could enable users to choose (zero weight) fonts instead of sometimes (unknowingly) overloading their sites with several web fonts.