Using iPhone memoji on Facebook messenger

I figured out a workaround to using iPhone Memoji on Facebook messenger. I sent several of my Memojis to myself on iPhone text messages. I took a screenshot of them. Then they appeared in my camera roll. Somehow they appeared in my sticker choices after that. It was trial and error. I’m not sure if the stickers will stay there but so far it’s a solution. They aren’t animated but since Facebook has no avatar choice available to me for some strange reason this is the best I could do. If anyone has another way to use iphone Memoji on Facebook messenger it would be appreciated. I don’t understand why other people can make avatars on Facebook and others have no option to do it. Must be a meta thing but their help area never answers as to why not. I have no avatar option on Facebook, but made one on Instagram and my profiles are across both.