Given that neither Cisco nor Juniper ever adopted support for running OpenVPN on their platforms, I suspect it's unlikely that they'd adopt support for Wireguard. I would venture that as far as appliance support, the best bet is likely to be NetGate and pfSense, but I think Wireguard is going to have to come out with an "OK, we're comfortable with being considered production-ready" statement first, given that the front page of their website right now still proclaims the opposite. Once that happens - and the ball is largely in Wireguard's court to move that forward - then we should expect to see more mainstream adoption into products like pfSense.