Demand for open hardware is loud, willingness to pay is not
"Will Linux phones become viable?" got the Betteridge's-law treatment, though one commenter argued Jolla's Sailfish OS devices already are a viable alternative. Another speculated that devs moving from CRUD work into low-level and hardware work with AI will push this forward.
The Ask HN about selling routers with DD-WRT pre-installed was blunter. Commenters said people who want it will flash it themselves, so it won't work as a business. One pointed out DD-WRT isn't actually open source and OpenWRT is. Others buy ASUS with Merlin firmware or GL.iNet hardware already, and one noted routers are "a pretty geeky thing" that most people don't want to think about.
The pattern: a small, vocal audience wants control over its devices, but it is technical enough to DIY and unlikely to pay a premium for convenience.
So what?
Don't mistake enthusiast enthusiasm for a market. The openings are in the gaps commenters named: central management of many OpenWRT access points, and products that a non-geek relative could actually use. Sell outcomes to the people who would never flash firmware.