i'm not sure if there is a conclusive answer to this already
i'm inclined to say it's allowed personally, and have been wanting to try it out for the adlib format for a while myself. i'm unsure of whether the submission should be .vgm or just .fur - people send in .mptm over .vgm i assume to match how you are sending in modules (instead of exports) for RAD, AT2, and s3m, so i feel like there's a case for that, but .vgm might be a safer bet, too, and would probably be what i'd try first.
anyway i think there hasn't been a real convo about this yet so it's a great time to have one, and considering how long the list of other options is, until it's ironed out i'd say go for it