I can’t speak regarding the other brands, since we don’t carry them, but the GMRS frequencies are already programmed into the Wouxun KG-905G by default. The KG-905G owners manual lists the default channel and frequency assignments, and they are standard for nearly all GMRS and FRS radios sold and used in the US.
GMRS radios share 7 frequencies with FRS. As such, you can look up these common frequencies and see if one of them is being used at work. The 7 500 mW FRS-only frequencies are NOT available on a GMRS radio, so if your work is using those frequencies, you are out of luck.