Discussed on slack channel (#lobby) with @christian Poessinger. He has the relevant original configuration file in PM.

Additionally, I've discovered that CURL uses libssh2 which doesn't support newer host keys (e.g. current default ed25519). Most hosts generate an RSA key as well, but using ssh to log into the remote host will, by default, only place the ed25519 host key in the authorized keys file. The following command:

I pushed it already. If you wish to re-merge, it's there.

So you merged while I was working on fixing the lint. If you care, I pushed an update with the line lengths corrected. Otherwise, feel free to ignore. Your call.
Thanks for the fast response and your patience with me.

That's fair... I'll try to have something in the next few days.

There’s still the issue of getting it added to the documentation.

Some additional information: Here's what happens after upgrading (the version I was running predated ip6gre support, so that was my bad)...
I try to configure the tunnel interface and get the following:

Thanks for that. However, encapsulation ip6gre is nowhere to be found in a documentation search on readthedocs.
As to why it got tased VyOS Manager, the tag was automatically inserted when I created the issue and no alternatives were offered by the UI at my userlevel.
Apologies for my ignorance, I am relatively new to VyOS though quite experienced with IPv6 and with routing in general.
Respectfully, I suggest reopening this ticket and recategorizing it to documentation appropriately so as to get the documents brought up to speed with the implementation.