SR-IOV and passthrough are mutual exclusion. If u passthrough NIC, you cannot enable SR-IOV.
if u passthrough the 2.5G port to VM, you do not need to install the modified driver on ESXi, but you need to install the modified driver on VM.

I never tested SR-IOV for 2.5G port.
Also, the original qfle3 driver for BCM57810 on 6.7.0 Update 3 (Build 15160138) has some problem enabling the SR-IOV, you have to upgrade the qfle3 to 1.1.12.0-1OEM.670.0.0.8169922
