Unless you’re looking for a retro games Mac or want to keep it as a collectible, the PPC Macs are not really that usable today for mainstream tasks. I would only fix this if you’re looking for a Mac for retro games, or just want to save it as a collectible.
The primary issue beyond OS support is the battery - like everyone else, Apple was bit by the 2006-2008/09 Sony battery recalls :(. Sadly, Apple has since pulled the info on how to check (granted, Dell also made it harder to find despite also being hit hard. I guess Apple and Dell logic is the people who still run these only want them for retro games, so they know to tread with caution on original packs), so I would either see what you can find, or replace the battery out of caution unless you know it’s not affected. I was able to find it on archive.is, but consider this a very lucky find; not all of it was properly archived.