Installing Nextcloud in user home directory on shared server

I’m using a shared private server, meaning we all have access to the root account for admin tasks. We hosts our websites in our respective home directories.

www-data can read/write in my ~user/www directory and I used a SGID bit on it to ensure files created by www-data belong to a group my user also belongs to.

It all works fine except some websites such as Nextcloud may write files (updates, user uploads,…) that are not group-readable/writable and then I end up with files in my home dir on which I can’t act upon (backup to a local computer, copy/transfer to another server as user, overwrite as user during a manual .tar.gz update, whatever).

I can become root, but this breaks the initial point of splitting web sites hosting in our user directories.

I know that the recommended ownership is www-data (see quote below) but is there a recommended approach to what we’re trying to achieve?

Upon further reading, I have the feeling that this should be achieved at webserver level, that is, rather than messing with file ownerships, ensure that each website (virtual host) is run under a different user, using the webserver configuration.

This is apparently feasible with apache (https://askubuntu.com/questions/422849/correctly-setup-apache-virtual-hosts-with-multiple-users) and nginx (https://serverfault.com/questions/370820/user-per-virtual-host-in-nginx) although it is not so common and it comes with limitations. Therefore, I’m interested in other users feedback.

(From this perspective, this discussion is not specific to Nextcloud.)