HP Z2 Mini G9 PCIe SFP+ bracket by teotwaki -

As above, possibly a PCI-E 1x ribbon extension or if your case has a vertical GPU mount or is a

Will the headers for front panel connections be blocked Does the graphics card get more performance depending on which PCIe slot it goes

gpu with m2 slot CPU Cooler blocking PCIe port

gpu stuck in pcie slot slot GPU, still allowing you to use any slots that a graphics card would otherwise cover up