The Mira cast is disabled by Android from Nougat. Pixel and Nexus 6p has the same issue. They are enabled only to support chrome cast.
But I am surprised to see that Android one device like MI A1 has the wireless display option to cast screen which is working perfectly.
So Nokia should enable this to help users. I hv a smart TV usually casting screen with older device but with 7+ it's not working.