If a device (whether it's a server, switch, router, or anything in between) supports port-channels (also sometimes called EtherChannels, Link Aggregation Groups [LAGs], bonds, etc.) using either LACP (Link Aggregation Control Protocol) or statically (meaning, no protocol is used to orchestrate port-channel members and coordinate bringing the link up), then you can connect the device to two Nexus switches in a vPC domain using a vPC.
One of the strategic advantages of vPC is that the vPC domain is transparent to the device connected through a vPC. In other words, the vPC-connected device (such as your server) has no knowledge that it is physically connected to two different switches. From the vPC-connected device's perspective, it believes it is connected to a single logical device (which is what the vPC domain emulates, even though in reality, the vPC domain consists of two separate Nexus switches).
If the Nvidia Mellanox ConnectX-4 NICs you plan on using support LACP or the operating system you plan on running on the server supports LACP, then you can connect the server to both of your Nexus switches through a vPC. For what it is worth, most hosts and operating systems created within the past decade will support LACP (and, therefore, can be connected to the network through a vPC).