Hello,

Here is _unofficial_ OpenVPN Windows client with wintun support:

https://staging.openvpn.net/openvpn2/openvpn-install-2.5_git-I607-Win10.exe

The installer includes wintun MSM version 0.6, wrapped into MSI according
to msi-example doc.

To use wintun driver instead of tap-window6, add "windows-driver wintun" to
your VPN profile.

Please be aware that openvpn wintun support has not been yet reviewed and
merged, so it may contain bugs.

Some performance numbers (with recent -O2 fix to windows build system):

Server - openvpn 2.4.4
    tap-windows6: 390Mbit/s
    wintun: 730Mbit/s

Server - openvpn3 with kernel acceleration
    tap-windows6: 405Mbit/s
    wintun: 1.05Gbit/s

-- 
-Lev