You can accurately detect the edges' sharpness and display all edges
detected as sharp when the Shading with Edges without Smooth Edges
view mode is active.
Notes:
The Sharpness mode is only a transient way of working you can use
to analyze the geometry when no command is running or for creating a feature.
Even with the Sharpness mode on, some differences with the
Connect Checker command may appear in specific cases, especially
when the sharpness along the edge varies a little bit around the limit value, which is 0.5
deg. Using such an edge is then not stable as many operators do not behave identically
with smooth edges as with sharp edges.