mkdir /tmp/opt
mount /dev/whatever /tmp/opt
mount -o bind /tmp/opt /opt
Works for me, may break things for you (I couldn't see anything actively running out of the read-only /opt path.
I don't recommend this, but it let me get Entware working to test things.
I bought an RP-AX56 to do some troubleshooting of devices that only work on 2.4ghz. I want to plug the extender into Ethernet and have it broadcast ONLY a 2.4ghz network. Is this possible? I can't seem to get the correct combination of settings to make this happen.