2. Is an absurd example. That is not how you do networked physics in 2026. You use jolt for cross-platform determinism with rollback, replicating only inputs.
Deterministic cross-platform networking with jolt is fine and good, but there are multiple ways to network a game, and even to do networked physics in 2026.
I hope your game world is small, and your player count is low, otherwise: 1) your server will be waiting for inputs from the most lagged player, 2) you will become entirely CPU bound on the client performing all this rollback.
Approaches that don't suffer from these two problems send state, yes they send a lot more bandwidth, but they scale better as the number of players n increases.
You are correct. You can do that. Then the real cost becomes the extra CPU cost of the rollback. Better not be CPU bound with that physics simulation, because you might need to roll back a whole second worth of physics in less than 1/60th of a second of real-time.
I hope your game world is small, and your player count is low, otherwise: 1) your server will be waiting for inputs from the most lagged player, 2) you will become entirely CPU bound on the client performing all this rollback.
Approaches that don't suffer from these two problems send state, yes they send a lot more bandwidth, but they scale better as the number of players n increases.