There are better sensors that are already deployed, they were developed in the 1970s so that submarines could navigate undersea with zero emissions by using a gravity gradient map of the seafloor, part of the Trident II system.
Gravimeters are already a thing and they're sensitive enough to detect accumulating snowfall on the roof of the building they're in.
Gravitational force can be measured very accurately by dropping a retroreflector in a vacuum chamber and measuring the acceleration with a laser interferometer. The clock comparisons explained in the article measure the difference in gravitational potential between two locations. This would normally require measuring and integrating the force all the way between the two locations.