Ouch... not to insult your intelligence but have you started walking? As in 2-3 miles at a time? If not, I think that is a good place to start. If you can do that, I would continually add distance and frequency. As for lifting, I would start low weight on leg machines until you build up the strength until strong enough for your historical leg day routine, I probably wouldn't start off with barbell squats hahah.

Here is decent work out routine for surgery recovery:

Box Squats (key for you)
-Sit back onto a bench → stand up
-Keeps shin more vertical → less ankle stress

Leg Press (feet higher on platform)
-Reduces ankle dorsiflexion demand

Wall Sits
-Great for endurance without movement

Goblet Squats (light)
-Only if comfortable—keep torso upright

Tibialis Raises (toes up against wall)

Band work (for surrounding musculature)

Hip Abduction (bands or machine)

Modified calf work (isometric holds)

These would be the exercises I would focus on until you are strong enough to hit the heavy weights.