It can definitely work. It comes down to how many step-ups you can tolerate (mentally).
I train someone with limited access to hills and a busy work schedule, so he’s become a step-up machine. And he’s raised his AeT HR by 12% due to his diligence. He uses a metronome and tempo-organized music (via an app) to control his pace.
He’s an ex-marine with an incredible work ethic, so I think that helps him get it done.
The one caveat with your idea is that the squat jumps could become a muscular endurance exercise which needs to be done carefully. Search the site for our articles on our gym-based ME program.