Growing on birch bark, possibly in association with the bright-yellow powdery lichen, that might be Chrysothix? In the past, I have found this lichen growing on spruce with Chrysothix as well.
Photo taken with a cheap digital microscope so picture quality isn’t the best but its okay. These little guys measured about 1mm tall. I would definitely suggest getting a handheld scope, I do use a 10x hand lens in the field but the digital scope is really handy and doesn’t cause eye strain.
i used to be on reddit identfying plants for people, i use google alot. but i came across some rare plants that were posted(mycoheterotrophs), the most tricky ones are succulents since many hybridize with each other and they often are very hard to distinguish from each other, as there is cultivars.