Yes you can flash OpenWrt as if you have the MiWiFi mini.
I'm currently using PandoraBox 19.01 on mine because the 2.4 GHz wifi is not stable for me on OpenWrt 18.06 (and turns out it is most likely fixed on SNAPSHOT, but I'm currently too lazy to change it), been running it non-stop since then (except a few blackout now and then).