Copy on write is likely to introduce significant performance decreases in cases where large or medium size files have a couple bytes changed. It’s usually recommended to turn CoW off on those files; I found it to be more hassle than it’s worth for a root filesystem. It is still a reasonable file system for file storage that looks more like archival - files land there and seldomly or never change. If you don’t have a specific need in mind though, I wouldn’t bother - in my opinion, it’s not great as a general purpose filesystem.

Personally I’d rather run one of these chips headless anyways.

That second error is not a matter of your ARM64 architecture, but a networking thing. If you launch a bash shell in your container, does any network activity work? That will tell you if it’s the container, or just Lemmy.

Is there a postgresql docker container running?