Most modern (digital) meters measure ambient and flash, or a combination of the two, with variables e.g. 40-60 split (this is the variable part).
For portraits outdoors in natural light, incident, reflective of spot; all have their definite uses. Flash is never in practice to be made the dominant illumination in outdoor portraits — enough, just a kiss, to fill / balance any distracting shadows and no more.

Not sure what a Nikkor 28mm f2.8 is worth but selling privately would be better than taking it to a dealer. Second hand market light meters would be much cheaper and a better choice when starting out than jumping in at the all-singing, all-dancing end. I started off with a Polaris meter many years ago which cost me $200 — way beyond my student budget at the time, but it did the trick — until it was stolen...