Yes you can get biodegradable glitter and this Etsy company sell it in compostable packaging. Yay!

Overview
Handmade item
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.

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Read more about compostable plastics HERE