There is a high expectation to work hard and engineers will frequently work evenings/weekends. Nobody will force you to, but the culture is certainly there to do this, mainly as everyone really cares about what they're working on and want to see it succeed.
As a startup there are clearly pieces of infrastructure that are still to be setup/built. This is great at times as I can work on things from first principles and really understand how they work, though there are also times I miss the efficiency of knowing a system is already in place with owners that I can just use, as you would see at a larger company