Forcing Access Point to launch?

Does shorting GPIO0 to ground on a ESP32 still cause access point to start?
Will this still happen if the ESP32 is currently connected to a network? I couldn’t get my devices to work this way.

GPIO0 to ground for >6 seconds will reset the Wifi config.

IS it OK to leave GPIO0 floating?

Yes as it should have a pullup resistor to keep it high with nothing connected.
Most all boards will have the resistor in place already.