I first going to link you three things:
1, A pinned topic just above your post:
https://steamhost.cn/steamcommunity_com/app/274920/discussions/1/613937306565587760/
2. A search for the word mac:
https://steamhost.cn/steamcommunity_com/app/274920/discussions/search/?q=mac
3. A news article by Holotech Studios
https://facerig.com/index.php?option=com_content&view=article&id=205:facerig-community-poll-results&catid=9&Itemid=128

(also, this is one of their latest replies on the matter: https://steamhost.cn/steamcommunity_com/app/274920/discussions/0/517142892057280312/ )


To summarize: they are already planning on working on a Mac releasse, they have even been planning for that since the Indie-gogo days ( https://www.indiegogo.com/projects/facerig ) but in the latest community poll, Mac came second to mobile devices. You also need to remember that:
Holotech studios is only a small indie company, with few employees and a limited budget, so they can't work on all versions at once, and have instead decided to work on one version at a time, make sure it is "done" and then move on to the next (of course still updating / fixing bugs in the previous platform(s) but it is but on a low burner.

Good Point Furriffic, maybe we should all donate if we're so flustered about Facerig not being on Mac :P