Unfortunately it’s not even close to 100% ethical even if you disregard the software. Have e.g. a look at the list of suppliers. There you’ll see that only a small percentage of the suppliers is working together with Fairphone on one of the supplier engagement initiatives.
There is a similar picture for the materials. Only a hand full of metals are sourced responsibly for the Fairphone. Fairphone identified the ones that are most impactful and started working on them, but there are conflicts and shortcomings with other materials. It’s a long way to go still.
As for the software: We know that Fairphone Open is “on the roadmap”, but that doesn’t necessarily mean that they are already working on it. Also I’m sure the community will port various alternative OSes soon. You’ll find them in the oslist when they are ready for use.