I get bored doing one thing just for the workout, but when schedules are tight and you’re stuck in flat country you have to do as much as possible inside and out.
A hunting buddy stopped by the house and said to put on hunting boots, we’re going to be side hilling all day. Turned out he volunteered us to pick up trash along a highway. All day side hilling, walking up, and walking down. Any landscaping on steep slopes is also a good ankle workout. If your town has a big white letter on a hillside, those always need help picking weeds and painting rocks. Volunteering to help build trails is full of off angle ankle workout.
Just going for walk anywhere that’s not flat is 10x better than flat established trails. Every city has storm water catch basins you can walk around. Urban bushwhacking off of sidewalks is full of clumpy grass which is also working the ankles. Rather than walking around a city lake with a trail, bushwhacking along the shore will be much better. If there is a creek of any kind, fly fishing is a lot of ankle work. Railroad right of ways are full of side hill action.
Inside I’ve built a short carpeted ramp 2’ square with about a 1’ rise in 3-1/2’ run. Standing on it at various orientations while watching TV will mostly highlight boot fit issues, but anytime you’re on the side edge of your boots that’s good. Even without weight, place a chair next to it to hold onto for balance and stay standing on one foot as long as you can, inside edge, then outside edge, then up on your calf. Boring as hell, but can be done anywhere. These ramps are also perfect for checking new boots for length - standing pointed downhill for 20 minutes your foot will be as far forward as it gets and the tip of your big toe will tell you if the length is long enough.
Humans are good at avoiding difficulty, so walking around staying off most trails is the single best ankle workout I know of.
