I had a discussion with a client about this a little while ago and it took me some time to find the link, but here’s VMware’s current list of supported Hardware VXLAN Gateways.
I’ve also been told there are some Cisco devices supported that aren’t on the list:
With OS version 7.0(3)I4(2):
The 9300-EX should join that list soon. I have no idea if or when supported Cisco devices will be made public.
There is an HoL (HOL-1703-SDC-1) that has a module on configuring NSX to work with an Arista (note that its a simulation, not a “real” lab) if you want some almost-hands-on experience.
If you have some physical devices you want to participate on a VXLAN network (maybe L2 connectivity is required or you just can’t change IPs), hardware VTEPs are one possible solution.