I don't think you understand what you have done.

When you have separate tickets, and you don't make it to a flight, it is not the airline's responsibility. They don't have to reroute you or do anything. As far as they are concerned, you overslept and missed the flight.

They may, at their discretion, rebook you IF seats exist, but they don't have to do squat.

Award bookings can be changed for free IF award seats exist. In the case of irrops you can be rerouted even without award seat availability. But you have to be on the same ticket to get help for irrops.