Very little. It's completely not a priority for me at the moment. I am 100% focused on this last lifting goal.
When I do ramp up the walking, I'll start at around 1 hr / day of active cardio, 5 days a week. If I need to increase, I'll gently increase the work rate (pace, incline, add a flight of stairs, etc) rather than increase walking time too much. And I'll add more passive cardio (like walking 1:1s) during the day.
That plus 1 hr of lifting, will be plenty.