https://screenspan.net/fallback https://screenspan.net/fallback is a good resource for finding out which system font looks most like the intended webfont, e.g.

https://screenspan.net/fallback https://screenspan.net/fallback is a good resource for finding out which system font looks most like the intended webfont, e.g. in my use case, Verdana has similar metrics to Roboto Serif.