One of my biggest fails this year for Christmas was buy a present that had glitter in it. It was only after I had brought it that I had remembered that glitter is micro plastic. I was pretty mad at myself for a week.
There is a shop called eco glitter that make biodegradable glitter. https://www.ecoglitterfun.com/
It seems pretty awesome. But in general, I think I'd rather avoid the stuff. It is super messy, hard to clean. Again I feel like a Grinch saying that glitter is something to be avoided, and it is rather depressing that I'm finding all of the things that used to give me some 'joy' no longer do so because I know of the consequences. But I do like that I'm finding new ways to spread joy and have joy.