Earlier quoted context omitted.
https://nebulasans.com/img/handgloves.png
I saw that. Here's a quick similar comparison between Nebula Sans and Source Sans I just whipped up: https://imgur.com/JPwgYkj
Glyph proportions between Whitney and Nebula are almost identical. As are their weights. Source Sans is substantially heavier and more dense looking.
While individual glyphs may be closer between Nebula and Source Sans, but the overall feel of Nebula is that of Whitney.