Bigger orgs for the most part use whatever vpn solutions their (potentially decade old) hardware firewalls support. Until you can manage and endpoint a Wireguard tunnel on Cisco, Juniper, Fortigate (etc) hardware then it's going to take a while to become more mainstream.

Which is a shame, because I have a number of problematic links (low bandwidth, high latency) that wireguard would be absolutely fantastic for, but neither end supports it and there's no chance they'll let me start terminating a tonne of VPNs in software on a random *nix box.