[m01]

I don't know if they specifically fit your bill, but the Turris devices are worth checking out [1]. They come out of the box with TurrisOS, which is an OpenWRT fork with some extra features (e.g. automatic updates, config snapshots) and some changes (e.g. knot resolver for dns). Turris are a bit opinionated about using DNSSEC, and I think historically it was a bit tricky to configure a custom DNS resolver, but it looks like that's now possible through their new UI [2]. By the way, they offer 3 UIs: Foris, reForis and OpenWRT's LuCI, and of course ssh is also available.

If you don't like the fork, at least with the Turris Omnia it looks like you can put on vanilla OpenWRT [3], but as always check the OpenWRT table of hardware for details before buying.

I think the PSU of the Turris Omnia is rated at 40W max, but I don't know what sort of real-world power draw you'd get with your specific use-case. I guess it depends on whether you use WiFi, the SFP port etc.

[1] https://www.turris.com/en

[2] https://docs.turris.cz/basics/reforis/dns/reforis-dns/

[3] https://openwrt.org/toh/turris/turris_omnia