I suspect they’ll become like OpenWRT routers where the stock firmware is total garbage but you can replace it with something open source to super power the device.

Honestly I don't imagine that as likely the case. Bottom line almost every practical use of AR that comes to mind, requires a ton of AI stuff rolling it in the background. Identify what shit is, who people are etc.... Without that you are basically just looking at a hands free camera. Guessing with small form factors etc... not much is going to be processed locally so we aren't looking at much that has value in the independent firmware space.