OT-SVG fonts are actually displayed on MacOS Mojave, just need to fix a tiny bug to be able to use them effectively ;)
Here's a screen recording of the issue: https://i.imgur.com/jkZXo3f.gif
Now that macOS Mojave support OpenType-SVG fonts, they are showing up ok in XD when editing text, but rendering is switching them back to greyscale when deselecting the text. And turns to black shapes when zooming in the text.
Issue on XD. 126.96.36.199 with both Gilbert and Trajan Color (no issue with OT-SVG bitmap fonts, only color vector ones).
+1 Can't wait to be able to use web fonts in XD, including custom web fonts created in Illustrator and hosted on Fontself Catapult https://www.fontself.com/catapult (disclosure: I'm a Fontself team member ;)