Yes you can get biodegradable glitter and this Etsy company sell it in compostable packaging. Yay!
Materials: Biodegradable Film, Certified as Compostable, Compost Home Certified, ISO 17088 2212, EN13432, ASTM D6400
And the bags and packaging it comes in are biodegradable too.
You can buy from EcoEquinox A U.K. Based seller.
Read more about compostable plastics HERE