Authentik is a very capable open source Identity Provider (idP software like Authelia, Okta, Keycloak etc.) which probably has the most features of any open source identify provider available. It's also still under heavy development with stable releases being made every few weeks.
Self-Hosting
Nextcloud supports pretty urls which is a fancy way of saying it will not display the 'index.php' part in the address bar. However its configuration assumes everyone is using the Apache web server and tries to utilize its .htaccess and rewrite mechanisms. Since some web servers like Nginx and Caddy do not provide these facilities, it won't work without some settings.
FreeNAS (and TrueNAS) keep track of system alerts and can be configured to send those out via email and a few other services such as Slack and InfluxDB. The selection of these services is pretty limited. Especially limiting is the fact that it does not provide a way to call a custom script or a web service endpoint. But we can capture the alerts from the system and get them out in a roundabout way.
Zulip is an open source messaging system that has a unique threaded chat model with topics for threads. Alerta is an open source alert management tool that aggregates alerts from various sources and displays them on an easy to use web interface.
FreeNAS (now TrueNAS) does not have access to FreeBSD's ports or packages. Normally extra software needs to be installed in jails. However sometimes you need software on the host itself. It is possible to copy program binaries from the jail to the host if you take care of a few things first.
I thought it would be kind of cool if `portainer` could upgrade itself using its gui. Alas it falls into a chicken and egg situation and you need to step in and use the console. Here's how to upgrade `portainer` safely without losing configuration data.