Am I correct in saying this Pi5 will be the best chance at a very performant desktop PC? That seems very much where they were headed with all these designs.
For not a lot more you can now get NUC like machines with Celeron's, Pentiums and get to choose NVMe SSDS and RAM amounts and even Wifi cards (so wifi 6e or 7) and 2.5 gbit/s ethernet. At these sorts of prices they are running into the low end of NUCs at $100 and they don't compete well on a whole range of factors. They are still cheaper but its not the 30-40 of the Pi before prices went nuts and this new higher price point isn't as clear cut.
AFAIK that's one of the goals of the ARM (and maybe eventually RISC-V) architecture. It's doing well on mobile and the low consumption is needed for a future that will require less energy. Or at least, do more with less. Having ARM desktops would also merge the mobile and the desktop environments.
Apple has moved to this architecture, and software wise, Linux is very compatible too. Even Microsoft knows and is trying (clumsily) to move to ARM.
The Pi5 will indeed open new possibilities on that front.
For performance you probably want something like a Orange Pi 5, in most workloads its significantly faster and uses less power doing so. But is also 20$ more expensive and probably doesn't have the community support around it.