My wife and I have three kids including one under 12 months. I use my own app Streaks Workout (https://www.streaksworkout.com) on an Apple TV (also available on iPhone and iPad) doing short, basic workouts. The older kids who are 4 and 6 love following along too.
I agree completely that time is exceptionally short with kids in the picture, but it’s not impossible to do at least something simple.