Hi, Temporos. Most Powerbook G4 models aren't able to boot into OS 9.anything, regardless of the disc being used.
All Titanium PB G4s, which have two separate hinges and most of their ports on the back panel between the hinges, are bootable into some version of OS 9. Some of them require the model-specific version of OS 9.2.2 that was shipped on the discs that came with them. There is no other source for a bootable OS 9.2.2 on those models.
The many different Aluminum PB G4 models (12", 15" and 17"), which all have a single continuous hinge running all the way across the back and all their ports on the side panels, can't boot into any version of OS 9. The discs that were shipped with them include installers for Classic, i.e. a non-bootable installation of OS 9 that can be used to run OS 9-based apps in OS X.
Whether or not your Powerbook can boot to an OS 9.2.1 retail installer disc is not dependent on having OS 9 drivers installed on the hard drive. Even without those drivers installed, a Powerbook that is capable of booting to a retail 9.2.1 disc will do so, if the disc and the PB's optical drive are in working order. But if the PB can't boot to that disc, nothing you can do will change that.
Please
identify your PB G4 model precisely. Then we'll know how to advise you.