As a courtesy to the next person who needs to figure this out: If you want to install Linux on a 2009 Mac mini (Macmini3,1), you need to use an optical BIOS-only install medium that is not EFI-bootable. Ubuntu and Fedora no longer appear to publish images like this. Debian, however, does.
Download the Debian netinst image with “mac” in the file name from the amd64/iso-cd/ directory. Burn it on a CD. Connect an Ethernet cable that leads to the Internet. Boot the Mac mini with the CD in an optical drive and hold down the “c” key. (If the built-in DVD drive no longer works, an external USB one is OK.) Choose graphical installation. Install the default Gnome environment.
You get a working GPU-accelerated Gnome-on-Wayland environment with Firefox running with WebRender on Wayland.
If, on the other hand, you try the more obvious route of writing the Fedora live .iso to a USB stick and boot it via EFI, you end up with nouveau complaining during the boot and after gdm starts, you get a hardware-accelerated mouse cursor over an otherwise black screen. If you start in safe graphics mode, the install results also in nomodeset graphics, with a jumpy mouse cursor and Wayland over software rendering. If you try to remove the nomodeset part, you end up with the same black screen with mouse cursor. You are going to have a bad time. You really need a BIOS-only install medium. Web search results suggest that you could use Rufus to turn an EFI+BIOS Fedora or Ubuntu image into a BIOS-only install medium, but this did not work for me with current or old Rufus.