It'd be great if open firmware could be commercially viable. Finding a business model is hard.
The OpenWRT One [1] sponsored by the Software Conservancy [2] and manufactured by Banana Pi [3] works lovely.
[1] https://openwrt.org/toh/openwrt/one
[2] https://sfconservancy.org/activities/openwrt-one.html
[3] https://docs.banana-pi.org/en/OpenWRT-One/BananaPi_OpenWRT-O...
Open to audits doesn't mean free software, it just means visible source. The business model for selling routers with auditable firmware is selling routers.
There's also Turris from cz.nic [1]. Technically they use a fork of OpenWRT with some convenience features like auto-updates, although it looks like you can run OpenWRT on (some of their routers?) if you wanted to [2].
Just declare that any router that can be flashed to OpenWRT without loss of functionality is allowed to be imported.
Open firmware would become commercially viable when IP is abolished
The business model is simple: Sell nice hardware at a premium, then sponsor and upstream improvements to OpenWRT.
If the software is an important differentiator (arguably, it is for things like Ubiquiti, but clearly it is not for most consumer routers), then release the patches under the Business Source License with a 3-5 year sunset back to BSD / Apache / GPL.