almost no software available for the G5. Maybe buy a used copy of Logic Pro Studio 9 or Final Cut Pro 7 but trust me everything will be super super slow. Even with the top of the line Quad Core Machine. Browser performance really sucks.
I use to own one.
Are you joking? There are at least some 10k ports confirmed to build on PowerPC, and while a few may build yet not work, most on those are perfectly usable.
The single area where options are indeed constrained is the web, but even there it is still far from “no software exist”. No Facebook and Signal, but Discord, Jabber, Tox work, possibly Twitter, e-Mail, ftp, privacy tools are there (tor, i2p). And I do not imply some relics from 2002, mostly everything is there in the current versions. This is just on macOS, but if you add in BSD and Linux, mostly everything is available aside of proprietary software like Adobe. BSD and Linux have acceptably modern browsers. (MacOS is in the process.)
I don’t really get complaints about G5 being slow. Yes, compared to M1 it is slow in most cases, but it is always the case that your hardware is not the fastest and some other thing is better. Quad is fast enough for most non-professional tasks. It is fast enough for some professional tasks. It is okay for development and testing. Yeah, it won’t handle 8K video from MacOS, because no drivers for modern GPUs. Maybe from Linux it will.