The question that I have to ask: what category of CLI apps (or even some examples) exist that are too complex to maintain a few versions simultaneously as native packages but are not complex enough to just use an OCI container for them instead?

The flatpak documentation has a semi-relevant page on setting up a flatpak repo utilizing gitlab pages and gitlab’s CI runners on a pipeline. Obviously, you’d need to substitute Gitlab Pages for a webserver of your choice and to port the CI logic over to Gitea Actions (ensuring your Gitea instance is setup for it).

A flatpak repo itself is little more than a web server with a related GPG key for checking the signatures of assembled packages. The docs recommend setting up the CI pipeline to run less on-commit to the package repos and more on the lines of checking for available updates on interval, though I imagine other scenarios in a fully-controlled environment such as a selfhosted one might offer some flexibility.

As I am teaching myself right now maintainable selfhost setups using popular apps (admittedly with Kubernetes vs something minimal in functionality like Docker Desktop), there is a lot of complexity involved in getting these services both functional and maintainable while also having to consider the security implications of various setups.

While I agree the concept of self-host is a good thing to advocate, I think the complexity and difficulty involved not just to do it, but to do it right is going to be a straight cliff of a learning curve for those not already technically inclined in databases, networking, and filesystems/block storage.

Honestly, taking the burden of being IT for a reasonable subscription cost for your efforts is a better way to go, especially if the setup allows for expanding your offerings to other members in a localized community.

Alongside many others, I agree that using QEMU through GUI frontends like virt-manager or GNOME Boxes, or even server-focused solutions like Cockpit+VM plugin or Proxmox layered on top of your installation.

I just want to note a decent point against other solutions like VirtualBox or the VMWare products that work on Linux: these solutions that don’t rely on QEMU almost certainly need the user to install out-of-tree kernel modules (that in some cases may also be proprietary). QEMU and its frontends don’t need out-of-tree modules in a majority of distros and can work out of the box with all features (given BIOS configuration of the host and hardware supports them).