A year or two ago, some users of older gear were able to get a white-label "replacement DVD for Tiger OS X 10.4"
direct from Apple sales support; they had to ask for an Operating Systems Specialist and after some time discussing
the matter with that person at Apple, only if the Apple person looked into their database and happened to Find it,
there was a generic installer with white label, for a reasonable fee, you could buy from Apple, but not listed in a store.
If you try this, be sure to have serial number of iBook handy, as well as method of payment, a cc; and optimism.
Same was said for the Leopard version of white label "replacement DVD" for the 10.5 system. And I have not heard
of anyone able to get (or not get) these white label replacement 10.4 or 10.5 DVDs lately. But they did exist.
Of course, the 800MHz processor series could not run Leopard 10.5, since the lower limit for processor speed to
run Leopard OS X 10.5 is 867MHz, the ceiling is higher than your vintage product. To be able to include a system
DVD with the hardware you have, the Tiger 10.4 version on DVD would be quite good. There also was a version
of iLife from that era which would give the user an actual system like a newer Mac had. The original included
install restore disc set, earlier than Tiger 10.4, usually included a fairly good set of (then) current software + OSX.
The original set, not available, would be in gray label; the 800MHz PPC-based Macs of certain vintage could
dual-boot. I had an iMac G4 800MHz that could start up & run OS 9.2.2 native. A pile of great software exists.
Most accessible only from correct original media & the matching series of OS9 or OS X. Or from Classic in 10.4.
In any event...
Good luck & happy computing! 🙂