emacs-svg-icon VS emacs-gl

For the buttons, check excellent svg-toolbar. Check also other libraries by Rougier, for example his recently released helper for dialogs, svg-icons, etc.

Yes, he also uses svg to render a canvas and images. You can also check work by Rougier (/u/nicolas-rougier), he usually anounces his stuff in /r/emacs. He has done a lot with svg, check his svg-lib and svg-icons.

A potential solution without font is to create icons on the fly. See https://github.com/rougier/emacs-svg-icon

By the way, why only for pgtk? It would be nice to have it without pgtk or xwidgets (OpenGL was avaialable via xwidgets since quite some time, as a plugin).

If you need some 3D viz, there is also an Emacs binding to OpenGL. I believe it works only on X11, but I am not sure.

Webrender is using openGL. There are existing work out there regarding this. https://github.com/Jimx-/emacs-gl . But I would prefer WebGPU API over opengl's if I want to do computer graphics.

There is also a module to do OpenGL. You will have to compile the module yourself, but it shouldn't be too hard. No idea though how well, if at all, it works on macos.

Generally, librsvg (svg.el), is your best option to start with graphing in Emacs. Alternatively, if you are really ambitious you could take a look at Emacs-gl if you are familiar with OpenGL. Those are your drawing library. On top of them you will have to create some higher level library to draw charts, you could either adapt/convert one existing from some of other projects, for example there are several popular and good libraries for javascript that could probably work well with svg renderer. Perhaps take a look at some of Common Lisp charting libraries and see if you can make them work on top of svg.el or emacs-gl. For example, cl-2d seems quite reasonable to port to Emacs Lisp.