Systemd supports overrides for unit files. Since it looks like you're just adding two values, you could just modify the existing unit file with a .d file.
ie, create a file: /etc/systemd/system/openvpn-client@vpn-unrooted.service.d/user.conf containing:
[Service]User=openvpnGroup=openvpn
That way you'll get any fixes in the unit file for openvpn automatically included when there is an upgrade.
Systemd supports overrides for unit files. Since it looks like you're just adding two values, you could just modify the existing unit file with a .d file.
ie, create a file: /etc/systemd/system/openvpn-client@vpn-unrooted.service.d/user.conf containing:
[Service]User=openvpnGroup=openvpnThat way you'll get any fixes in the unit file for openvpn automatically included when there is an upgrade.