As a starting point, see this like: White On/Off Switches recognized as outlets - #2 by jvm33 for how to make the switch appear as a light.
As a point of clarification, “Smart Bulb” mode means that power is always sent to the load (i.e., the ‘Smart” bulbs will always have power which is needed to maintain their network connections). The switch will still report itself to iOS home as being “on” or “off”, but it really isn’t changing the power output - power is always on. What you will need to do in Smart bulb mode is to set up automations to respond to the On / Off state reports from the switch to trigger your automations and, in those automations, you have to control the bulbs directly. Is that what you are trying to do?