Yes, you just need to make sure that the middleware is deterministic, i.e. if every client sends identical inputs to the middleware, then it will generate the same outputs for each client.

If the library is deterministic, then yes, you can use it for lockstep networking.

If it's not deterministic for whatever reason (floating-point rounding across Intel/AMD without the right control bits, use of rand() or other static state, etc) then you'll have to decide on one particular node making each particular path planning, and sending that path as "control data" to all the other nodes. That can still be lock-step. Instead of sending "user sent unit A to location B," you send "user set unit A to walk across the path P," which everyone can follow deterministically.