Are M.2 M Key Nvme SSD to PCIe Adapter AIC supported in Catalina/Mojave?

My motherboard supports 2x m.2 drives and if an NVME drive in is the slot #2 then:

1. PCI_E2, PCI_E3, PCI_E4 and PCI_E5 slots will be unavailable when installing M.2 PCIe SSD in M2_2 slot.

Does this mean I'd be unable to use a secondary GPU for Qemu pass-through if the M2_2 slot is populated?

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If not then would the speed of one 970 evo be hindered much by this adapter, below 2500mb/s and/or is compatible with an OSX KVM?

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Thanks in advance!