Not just for inputting alot of commands, but making it possible to simply specifiy an opevnpn config instead of having to re-implement every possible openvpn setting using the VyOS syntax would be a huge benefit.
Not to mention the automation aspects.. copy config, load it. done.

We have thing like this in dhcpd's config - there you can state something like "subnet-parameters ... include file".
I was thinkking a little bit on it and came to the following idea - may be we should implement general syntax for stanza like "hey, vyos, I have config file for this service, please use it as is, but I still need the service to be operated on by vyos CLI commands". How do you think, would it be a good option to implement @dmbaturin?

I agree with the above, this is actually how I'm dealing with custom options with dhcpd at the moment, however the same can't be done with openvpn as the functionality to include files doesn't exist within openvpn's config format, whereas it does with dhcpd.

Also, with dhcpd you still have to escape values with " for quotes which is super annoying.

Some of the options can be included in the config:

set interfaces openvpn vtun10 openvpn-option-include '/config/openvpn/included.conf'

Just configure minimal OpenVPN configuration and include what you want

Although this works, there’s still some mandatory config statements that are required. You can just lob everything into a file to be included.