I'm not thinking accesing the Luci interface on the router remotely, I'm thinking using a local version of Luci to an OpenWRT router that doesn't have Luci installed.
That's (kind of) exactly what I was looking for.
I don't really understand the inner workings of Luci, so I don't know if it's the same that's being discussed on that thread (I'm reading still), but it's similar: have an app (could be a webapp that can be opened by any browser in any platform) that reads the configuration on the router, modify the parameters that you want, and send those changes in form of commands (or maybe just something like a configuration file in Luci).
I do beleive this could be useful to those low powered routers that are losing support because of low storage/RAM and but could still work without the web interface.
An option for you to try is to make your changes using luCi on the OpenWrt router you have, then Save rather than Save & Apply, click the button in the upper right corner and it'll show you the uci changes which are going to be made. As in, it'll give you the CLI commands for what changes you made.