There are dozens of suppliers in the HoloLens 2/IVAS including some who are very open about it, like Intevac. There are hundreds (or thousands) of suppliers to Microsoft in general. MicroVision got picked for Reddit speculation because it was an easy stock to pump.
The fact you use StockTwits watchers as a source for DD is laughable. Even today, after one year+ of non-stop pumping, the average American has no idea who is MicroVision. As for STM, they are very well known in manufacturing circles. You can open almost any electronic device in your possession and find one of their parts, similar to Foxconn. The only current product MicroVision might be a part of is HoloLens, maybe.
Could Microsoft make their own components? Microsoft paid for development of HoloLens. It is their component. They paid for it. They can find another parts maker and drop MicroVision altogether. The only ace MicroVision had was that they assembled the parts but they gave that up too.