I learned something about stretching that increases flexibility by a lot. It’s kind of hard to explain so I’ll give the simplest example. If you sit flat on the floor and try to touch your toes try pushing your heels into the floor. Seems counterintuitive but it works and you can use the technique on any stretch.
> Chest = push ups, overload with weight vest
> Shoulders = pike push ups, progress to handstand push ups
> Back = pull ups, or one armed ring rows, overload with weight vest
> Legs = Squat progressions, overload with weight vest.
Something like that alone will get you extremely far if you commit to it. If you're willing to introduce small weights you could alternatively do something like Simple and Sinister. Cardio is also a must for functional fitness. Shadowboxing is an underrated option for this. It has no harsh impact on your joints over time like running or burpees, and it'll get your heart pounding in no time and has zero equipment or space requirements.
* Barefoot jump rope on a soft surface
* Sprints, especially hill sprints or bike sprints
* Nordic hamstring curls in addition to squats
* Oblique twists with bar
* Farmers walks, especially offset (different weight in each hand)