Whoo. It's been a while since I was here. To answer the question of deadlift alternatives, there are very few that are worthwhile. If space is limited, dands are a good core exercise, along with plank position and bridging.
There is an exercise called a "good morning" that will work your lower back like partial deadlifts, but you need to go much lighter and pre- exhaust your legs. So maybe leg extensions and leg curls followed by lighter good mornings.
I really don't like good mornings, I think they might be risky. But I've had a back injury for years, and i don't trust any movement except back extensions and partial deadlifts. And because my back is so bad, I do light weight in these movements. I treat back movements like rehab. Someone with a healthy back will have a lot more leeway on the weight. And I endorse Partial Deadlifts as adaptable and safe. Partials can be done as heavy or heavier than breathing squats, and in fact are better for some body types.
A Partial is done the same way as a standard deadlift, but the bar is set so it starts just above the knee. I use cinder blocks to lift my bar to the start position.