I just set up something similar a couple weeks ago because I wanted to upload named album folders as albums into immich.
Workflow is:
Syncthing to sync phone folder to folder on unraid server.
2nd syncthing instance to sync above folder to "photo albums" folder.
Immich-go cron job runs hourly to upload photo albums folder to immich
I used immich-go because the CLI upload with album tag kept failing and apparently it's a common issue so.. ¯\_(ツ)_/¯ immich-go worked first try.
Now all my photos are uploaded as albums with no manual input: