Do you really need the x,y grid to be variable? Otherwise, you can use the heightfield shape that was just added to sprite mesh - check it out.
https://kindeyegames.itch.io/construct-3-cannon/devlog/635793/add-heightfield-sh...
If heightfeild does not work, can you show some screencaps about what you are looking for? (Sadly the cannon-es trimesh shape is not fully implemented it doesn't collide with the majority of other shapes.)