For OpenWRT users, there's even simpler: use the "adblock" and "luci-app-adblock" packages :) .

https://github.com/openwrt/packages/blob/master/net/adblock/...

https://openwrt.org/docs/guide-user/services/ad-blocking

https://forum.openwrt.org/t/adblock-support-thread/507

Never heard of smoothwan but I've been running PiHole on LXC on OpenWRT for years. It was never difficult to set it up, I just created a Debian (or Devuan, can't remember now) container and ran the PiHole install on it.