Is replacing icons with emoji a good idea?

I'm currently polishing an application I have built using fontawesome. Due to fontawesome's pretty huge (nearly 2 MB with the more accessible SVG + JS Version) footprint, I'm considering to utilize emoji instead. These are already on every machine and users should be used to them.

I think it might be a good idea since using icons the users already associate with their meaning might make it easier for them to quickly understand what a button does, even without reading the associated text. This would be especially good for illiterate, visually impaired or dyslexic users.

There still is the text for screen reader users and the icons are wrapped inside elements that are hidden from them.

The only caveat I can come up with is that Apple doesn't allow apps that use emoji in their interface sometimes. However this application is company internal and will never show up on any app store so I don't think this would be an issue.

As far as I can tell, all users have OSes that support emoji.

Is there anything I'm missing?