Wow, bold decisions for what it'll support and not. I like that it's laser focused on a specific use case. What do you think about the impact to instances' federation queue when a bunch of single user instances follow a community? 10x the traffic and queue for 10 single user instances than one instance with 10 users.
I ask this as someone that ran a full single user lemmy instance right up until recently and switch to a public piefed due to the traffic multiplication and other concerns.
I didn't intend and don't think the stick bit stuff will or could be a complete solution for you. You've got some oddly specific and kinda cruddy restrictions that you've got to workaround and when they get that nonsensical one ends up solidly in "cruddy hack" territory.
From the article:
group + s (pecial)
Commonly noted as SGID, this special permission has a couple of functions:
If set on a file, it allows the file to be executed as the group that owns the file (similar to SUID)
If set on a directory, any files created in the directory will have their group ownership set to that of the directory owner
You could run something like https://pypi.org/project/uploadserver/ in screen or run a cron every minute that just recursively sets the correct permissions.
I'm not the OP and only did a bad job cross-posting it but I do encourage you to print a bunch of these out!