Thanks for the tips guys.
High performance is not a requirement per se, I am in a (delayed) plan to move with my family to Spain in the next months (when the pandemic permits), so in my plan, the Mac Mini fits because it's small, portable, I could take with me to Spain. And I found one in decent conditions, with the lowest price I have ever seen here in Brazil. I still haven't bought it.
@AphoticD: Maybe the Mini would benefit from a upgrade to a small, cheap SSD? I didn't want to spend much money on it, when the plan is just have a bit of fun with it.
Definitely, Tiger and macOS 9 are of my interest here. I have a macOS 9 QEMU VM, so far I love it. Classilla definitely needs improvements. I am yet to do a QEMU Tiger install (this weekend will be perfect for it).
Last night I tried to make a QEMU install of Debian 10's PPC version, but after an hour or so of installation, when it completed and I had to reboot, there was an error and it did not boot, no matter how many times I tried. Ah, damn.
For now, I think it's better for me to keep doing my thing with the emulators, until I get more confidence to get the real thing for everything I want to do with it. The only real PPC mac I have ever tried was a G3 almost two decades ago, when I was in a lab at university doing my graduation in advertising and marketing.
I have two empty Mac Mini 2006 enclosures though, missing the rear and bottom parts. They were part of a (failed) plan from five years ago, an attempt at doing a small hackintosh.
I might have to cheat and put something else inside one of these enclosures, then resort to QEMU emulation for it: a Raspberry, a Intel NUC or the "expensive" mini AMD Ryzen computer, which would be great for any gaming when not doing my things.
It wouldn't be the first time - I've helped my 63 yr old dad to use a Raspberry to create his Apple IIe clone with Linapple for his nostalgia fun, it boots straight to Linapple and he's presented with a ProDOS screen... he's quite happy with that.
Again, thanks for the info!