Create an assisted teleop planner/controller/BT such that someone can teleop a robot and make it do things but use costmap information to make sure it doesn't run into anything or go somewhere it shouldn't. Maybe have an elevated permission BT branch so that someone can send commands to collide if appropriate.

Potentially make it semi-autonomous as well

Node take in output of joystick, teleop pad, etc and test that command til N seconds in the future for validity. That way always N seconds from collision at the given speed and vector commanded. Do so in the BT or as a planning plugin?

Or how nav1 did it https://github.com/ros-planning/navigation_experimental/blob/melodic-devel/assisted_teleop

Do a bit of research, find the options, select the most sensible for the behavior tree and nav2 structure.

Might be useful to have a teleop global recovery for a user to joystick a robot out of a bad situation and hit "ok" to go back to autonomous navigation via the BT.