did you try this one
Cavity / screen curvature EEVEE
but can also use new bevel node
or this one here
there is also the zebra nodes set up
might work!
you could at the limit go back to 2.49 which had a built in
curvature parameter/ function and render it in 2.49!
there is an addon call curvature2D which seems to be related to freestyle
may be someone can enlighten us on that function!
happy cl