Help me implement system UI fonts in SS 7.1

I'd love to implement "system UI" fonts. Those of you who are familiar with this, will know its advantages but also that there are different ways to implement. Obvi, I'm looking for the right way to implement this on my SS website - without uploading multiple font family files. On Google, you'll find tons of info, opinions, etc. on the topic, including: https://infinnie.github.io/blog/2017/systemui.html. I haven't found a SS resource, forum entry, or articles covering this topic but I'm positive there will be lots of interest in it. Thanks in advance if you're able to help out here.