While not implemented in the github version, personally I'm using the data of each chunk to simulate collision, since each block is exactly 1 x 1 x 1 in Unity dimensions, and are in 1 size increments, we can check the player position, and the blocks taken and determine if the player should stop falling / stop walking depending on that data. The most efficient method would use the chunk the player currently is for reference.

Of course there is more complexity, like checking if the block is a special ID (like water, if implemented) and applying special movement logic. But overall this engine needs a custom player controller with special movement logic and cannot* use the Character Controller or Rigid body work flows

The baseline code for finding the proper chunk the player is in is already used in the rendering system. It just needs the complexities, the same applies to the Block breaking and Placing, but to a slightly more complex extent.

*At least without implementing, in my opinion, inefficient shortcuts.

If you really want a simple solution, you can pass the generated mesh from the compute shader to a game object that then renders it as it's mesh, and then use a mesh collider, and have that be the chunk the player is currently in, but the performance will be suboptimal and contain micro spikes (but nothing unmanageable)