This is the official thread on the snap system …
it is under development, it has been for about three months until blender 2.81.
Actually is stopped, but presumably it will be resumed later.
this is the to-do task
Snapping & precision modeling improvements
(the tasks expected but still to be developed)
T69342: Snapping: Make ‘Absolute Grid Snapping’ a new Snap Mode
T66427: Snap to Grid in Perspective View performed only at ground level
? Hot mode switch: Ability to switch snap type during using tools via hotkeys
? Change the current behavior of the incremental snap (Snapping according to the distance to the snapping point and not to the grid)
? New ‘Snap With’: Cursor
? Improve look of the ‘Snap With’ Closest (drawing boundbox ends)
? New tool for “drawing” edges on a specific offset
? Support for snapping to Lattice objects