My personal applications tend to use only monospaces fonts and stick to Latin characters so I can get away with glyph rendering and then a very simple layout algorithm so something like ab_glyph or freetype is enough and I don't need harfbuzz.

I'm aware of swash and the other libraries in that stack, but it was going through a rewrite. The Linux support was incomplete, for example, it was dependent on a piped call to fc-list and parsing the output to get the system fonts.

Also, if I were doing it via web, I'd be tempted to render to an offscreen canvas and call it a day.