Those are more for color calibration. We are looking for just brightness measurement. The Minolta looks like the high end of those we found.
We decided to get a ~$150 Extech meter, that has the opaque white typical light meter. We will get relative numbers, rather than trusted absolute, but that is OK for now. Not sure what equipment is required to verify something like 300 nits for a smart phone screen, but it is probably fairly pricey.