Hi, Kim!
Are you doing this because of injury? And you can't use ankle weights?
I think you can maintain for a while at least with unweighted floor work. It's not as efficient as standing work (where each exercise can hit many muscle groups at once), so I wouldn't expect huge changes. But depending on what workouts you choose, you could have different results. If you do a workout that usually uses weights and has low reps, I would think you'd not have as good results as using a workout that is specifically meant to be used with no weights (and usually more reps).
I don't think you'll be wasting your time. The alternative would be to do no leg work, right? So anything is better than nothing.