There is also https://en.wikipedia.org/wiki/Shape_dynamics, which takes Mach's principle as a philosophical base and tries to rebuild (continuous) spacetime on top of it, basically by observing that any triangle with the same angles but different lengths is actually equivalent -- you can only measure distance between two things if there's a third thing that can see both of them.

It's been proven to be locally equivalent to General Relativity, but might differ globally (e.g. solving the bucket in an empty universe issue).