Interesting! Yes, something like that would be relatively easy to make for any number of pieces.

You could probably generate the shapes automatically via something like voronoi diagram cells plus some rounding of corners?

I haven't seen exactly that here in the US, but I've got some puzzles that aren't just knobs on 4 sides. Quite a few of the pieces are slanted, have 3 sides, sit at an angle, etc. It adds quite a lot of variation without breaking the interlocking nature of the puzzles we are used to.

Edit: I just realized that for kids, those knobs are easy to break off. The puzzle you showed makes more sense for kids.

My family has a collection of home-made jigsaw puzzles (literally made by a guy cutting up a wood-backed picture with a jigsaw) which look similar in terms of shape to that (but more pieces, 500 or so). I think they are much more interesting to solve, especially since the contours often follow the shapes in the image, which adds some twists in the difficulty. I would also be interested in finding a way to buy such puzzles nowadays (especially since they would in priciple be easy to produce through laser-cutting).

Don't know if this is originally japanese, but we have some puzzles like that in germany. One we have at home has a frame background image different to the puzzle motive. Adding visual disturbance. My kids seemed not to be disturbed as much by it than their parents in the first try