I personally don't like the concept of having my terminal send my commands to a remote service, so I'll pass. Hopefully an open source model comes around soon so stuff like this can be implemented locally.
That's afaik already the size when using half precision. And it's not like GPT3 doesn't get half queries wrong as-is in its optimal form, detracting from it will just make it unusable. Check out GPT-J if you want to see a functionally useless model that can be run locally.
It's not like this is something that can be surmounted without extra storage, neural nets are just a fancy system for compression and data access. You can either go for less data or more compression but either way your results won't ever be as good.