I run this same setup. Do you have any issues with inviting others to calendar events? If i invite via fossify on my phone it never gets sent, but if i do it from the Nextcloud UI it goes through without issue.
My most recent one I got working was Gluetun. And yeah in order to use it I have my entire arr stack in the same gluetun pod. The http proxy also works but I only wanted that as a last resort.
I always appreciate people putting up quadlet content. I've switched over almost my entire lab to it aside from Nextcloud (so thanks!) and a couple containers that have weird network quirks
I also started off with a converted gaming PC. I went with unraid because there was a simple path to upgrading my drives. I started off with 1 and 2 TB drives and eventually upgraded over the years to 12+ TB drives.
From my brief research back then growing a pool in freenas was a headache where upgrading in unraid was easy.
What scanner do you have? My biggest hurdle in making real use of paperless revolves around the annoyance of using a flatbed that's not within arms each of my desk lol