Yes. But that would assume that OP is not behind CGNAT.
Also, even with Static IP, if I had to just do file transfer over SSH, I would use Tailscale over selfhosting wireguard. But that's my personal take on this.
Just to share my experience. I was part of r/HomeAssistant for a year or so and I had no effing clue what it was or what it does. One day I was scrolling through YouTube and there was a guy talking about HomeAssistant. Only then I realised this is not some "Alexa/Siri" kinda home assistant. This is a home automation kinda thing.
Haha, I still laugh at my self for being an idiot for the whole 1 1.5 years.
Just throwing out an idea, could you create an smb share from nextcloud.
Mount that smb in the server that hosts Immich( even if it's the same server that hosts nextcloud).
Now, in Immich add an external library. The path of external library could be the smb mount.
Because buzz-all drinks.