Ruida controllers don’t use G-Code, but (some) can add delays so the exhaust air blower gets up to speed and clears the fumes at the end:
My KT332N controller has delay settings for both assist air and the exhaust blower, but I use a manual control for the latter. My version of Sadler’s dual-flow assist air plumbing works fine, with the controller set for 1 second on/off delays.
The G-Code commands originally controlling coolant flow have been repurposed for assist air, some controllers have additional (hardware) outputs that can control exhaust blowers (or other things), and all of them have programmable delays. G-Code dates back to the beginning of the CNC machinery era and, believe me, G-Code has capabilities lasers never touch.
If the controller you’re using lacks hardware outputs for your purposes, because the manufacturer has cost-optimized them out of existence in a specific machine, then you need a controller that meets your needs. Configuring that for a specific laser machine it was never intended to control will present a challenge educational opportunity, but will be more straightforward than trying to work around the limitations built into specific hardware.