in Redhat based distro you need to create and tap interface and ovs bridge by NetworkManager and nmcli command to make it permanently and usable by openvpn
in ubuntu and netplan env you just need to create ovs and tap interface by netplan config like this :
network:
version: 2
bridges:
br0:
openvswitch: {}
dhcp4: no
dhcp6: no
optional: true
addresses:
- 172.16.16.9/24
interfaces:
- tap0
ethernets:
tap0:
optional: true
ovs-if-br0 2c814735-7796-44e4-b665-0f11e3e9b042 ovs-interface br0
br0 561f4800-cdff-4ee9-b8d3-37a5bc12414b ovs-bridge br0
ovs-port-br0 d32517b7-66c5-47a0-b4ef-24a7b027c009 ovs-port br0
tap0 76c6e78b-13f4-43e4-b1cc-f77232ce41d4 tun tap0