Nextcloud App to display Free and total disk space in navigation bar

Hello Dear community and developers

I would like to ask a Question about advanced app development for Nextcloud.

I work for a Cloud Hosting Provider which offers a hosted Nextcloud Instance service. These Instances have Filesystem Quota to limit the disk Space per Customer.

In order to display that Quota to the User we hacked a patch for the files app which adds a second Quota Bar beneath the already existing one in Nextcloud.

This works but has not made it into production yet, due to the fact, that this patch is a pain to rebase every update.

I am looking into making that patch into it’s own app.

I read the documentation and the Tutorial but I did not find a function reference that allows me to inject a custom PHP snippet into the Navigation Menu. Is it possible to inject a custom template at a given place into the navigation bar?

If so would anyone have a link for some code that does that?

Thanks you in advance for any tips and ideas