How far can you go using just near-field probes?
Near field probes that I know of measure one-half of the emitted EM radiation - they are usually inductive loops that just pick-up on the magnetic part of the radiation. As the name suggests they are near field probes and, in the near field to a potential radiator, a full EM wave has not formed so it is correct that a near field probe only measures either the electric or magnetic field strength.
At some distance from the "radiator" (usually about one wavelength and greater), the E and H fields can combine to form a proper EM wave but, this cannot be determined by near field measurements because some "potential radiators" produce near field signals but are very poor at being a far-field antenna - luckily, these don't pose a problem but, you can't really tell that with near field probes.
In answer to your question I'd say "no".
Home-brewed equipment with a reasonable antenna can give quite decent results especially if you have previously "calibrated" results with "test-house" results.
We can’t give exact design but principle is this.
It is critical in EMC design to understand source/load impedance and voltage or current of both signal and interference from any source over the entire spectrum from DC to RF to ensure high S/N ratio. You can use STP or coax with <100 pf/m est. with filters, and CM chokes when necessary.
Ferrite beads are like lossy RL similar in low pass response with RC (xx pF) but raises output Z(f), while RC lowers Zo(f) .
CM chokes do better if high CMRR (f) is needed.
Start with SNR goal then test for this. When achieved your design is successful. Experience with all parameters above determines how to save time in choices for signal integrity, loading and compatability, EMC.
Proximity orientation and balance of actuator noise current-cable help when coupling is radiated. Quality and choice of earth ground is also significant. Search for any keywords above for details.
If you use strong pull-up then driver must be much stronger sink. ~50-75ohms for 74HC @5V, margin is defined by attenuated noise AND DC shift. Thus trade offs. e.g SCSI uses pull-up/down for optimization.
For logic consider using Interleaved gnd ribbon cable or UTP or STP or CAT x cables and RJ style connectors
Analog and digital grounds must be carefully selected common connection point near PS source, where currents are not shared. When source is noisy SMPS, then CM noise can be high and reduced by raising CM impedance >1MHz with CM choke or often best with low Z(f) earth gnd.
Keep in mind high current spikes in skinny tracks, are Inductive and high impedance // tracks have mutual coupling.
Best Answer
Everything is really tiny compared to tracks on a PCB so loop areas and potential antenna lengths are probably 10,000 and 100 times smaller respectively for a broad-brush and sweeping estimation.
Consider an unintentional PCB loop antenna that could spuriously transmit (or receive) interference - how much smaller will this be on a chip - dimensions of area might be 10,000 times smaller hence a distance of 100:1 doesn't seem unreasonable and it's probably a lot less - consider how far tracks are from the substrate (relative ground) of a chip - 100 millionths of an inch or maybe a bit more? PCB tracks above an earth plane are a much, much wider gaps.
I'm not going to give you actual numbers because it will vary between one device and the next but just consider that to make EMI or receive it you need something like an antenna - think how small and ineffective that will be on your average chip.
Having said all of that, chips aren't exempt from EMC but it takes a lot more energy to get a chip to roll-over - this energy will be likely more than enough to create a foul-smelling signal on a PCB track that might connect to the chip. How could you ever get a PCB track that could be as resilient as "the chip" - it's always going to be the PCB that causes problems not the chip.