A "select all that apply" option for custom approval requests would be very useful. From there, a switch function could be used to create different cases to cover all response combinations.
For example, I'm currently trying to make a flow that asks a manager for approval AND ask if any of 7 different departments are required to approve as well. With the current system of approval, to my knowledge, this can only be achieved by sending 8 different "yes or no" style requests to a manager. With a "select all that apply" option, this could be done in a single request.