I haven’t ever seen those nutrients sensors you link to, and I’m highly suspect. The closest thing I’ve seen are XRF guns and those are for metals.

The whole fertility sensor/probe thing is a pipe dream IMO. Soil heterogeneity is tremendous.

If you want an accurate reading, a lab is a must. Even then, parameters such as soil texture can vary by 10 to 30%

And electrical conductivity is never good. It’s routinely screened for along with SAR