Hi,
I tried searching for this, but most of the results were from 2015.

I've been working on restoring a couple of PowerPC G4 and G5 iMacs. Naturally I came here to look for some older games to run on it, but pretty much everything seems to require Intel Macs.

I imagine there probably isn't much money in supporting games for long-dead architectures, but I thought I'd ask anyway if there's anything for those old systems that I'm just not spotting. Or maybe there's another storefront out there to peruse?

There's nothing here that would work on PPC Macs. You might be able to find some physical copies of old games on eBay or something. Other than that, Spiderweb Software has some older games that run on PPC on their site. Ambrosia used to; not sure if they're still active.

Ambrosia, sadly, seems to have shut down a few years ago. The website is still up, and the downloads should work, but payment and code renewal don't.

I feel your pain though. I have a few Macs running "classic" (most of which can't run OS X at all) and software for that system is getting difficult to find (since the platform was far less popular than DOS/Windows, second-hand software is also not nearly as common).