My recommendation is to use an abstraction layer that runs qemu-kvm under the hood and automate that. Some people have mentioned libvirt, but Incus is another good option.
Owncast is the self hosted stream thing. It has some rudimentary federation capibilities, but nowhere near the ease discovery of twitch.
I know some streamers that have an owncast, expired_popsicle uses debian Linux and has one. (It's tech/linux streamers because of course).
go run works by compiling the program to a temporary executable and then executing that.
can you guarantee that runs everywhere
It seems to depend on glibc versions, if that's what you are asking. You can force it to be more static by using a static musl python or via other tools. Of course, a binary for Linux only runs on Linux and the same for Windows and Mac. But yeah.
Also it should be noted that go binaries that use C library dependencies are not truly standalone, often depending on glibc in similar ways. Of course, same as pyinstaller, you can use musl to make it more static.
You can create static binaries that bundle the python interpreter and dependencies.
It's the onefile option in pyinstaller: https://pyinstaller.org/en/stable/usage.html#cmdoption-F
You can also do it with C. Or Csharp. Or many other programming languages. It's not a feature unique to Go, it's just that Go can only create static binaries.
oh I have tested this game somewhat, although I've never actually played it. It is very impressive.
What about a static site generator? Plaintext, markdown, but renders to html with headings and whatnot. Version control is because it's in git.
Read access control is difficult though. You could do some hacks like using encrypting files in the git repo (perhaps with SOPS), and then either using http basic auth to control access to specific pages or something like staticrypt. But these are not ideal solutions.
Docker compose's don't really need to be maintained though. As long as the app doesn't need new components old docker composes should work.
EDIT: Oops, it does look like spacebarchat's docker images have last been updated over 2 years ago:
https://hub.docker.com/r/spacebarchat/server
EDIT2: Although this is outdated, I think their github repo has an action to autobuild docker images on pushes. Still investigating.
EDIT3: Okay, they don't seem to be actually ran.
But using nix to build a docker image is pretty cool.
EDIT4: Oh shit, the docker image build workflows were added just 2 hours ago. Of course they haven't been ran!
Docker support soon, probably.
EDIT5: the workflow ran, but it looks like it's private for now.

There are many, I think. Like what other people have mentioned, sometimes the new standard is just better on all metrics.
Another common example is when someone creates something as a passion project, rather than expecting it to get used widely. It's especially frustrating for me when I see people denigrate projects like those, criticizing it for a lack of practicality...
https://www.youtube.com/watch?v=46MQ1ZMZ-l4
This is a trailer for NBA 2k20, that shows more gambling content than actual gameplay.
The top comment is:
Hey 2k, theres a basketball minigame in your gambling simulator, can you fix it please?…
Termux recently got moved off of the play store (kinda), and is now only available on f-droid/github, because Google was further locking down what they allowed on their store.
And in addition to that, they recently added a restriction in later versions of Android: "Child process limit". Although this limit used to not there, when enabled, it prevents users from truly running arbitrary linux programs, like via termux.
Although the child process limit can still be disabled in developer options, it doesn't bode well for how flexible base android in the future will be, since many times corpos like Google move stuff into the "secret" options before eventually removing that dial all together.
TLDR: Termux has been, and is a thing... for now.
Also, I want to shout out winlator. It uses a linux proot, similator to termux, and has box64 and wine inside that proot that people can use to play games. I tested with Gungeon, and it even has controller support and performance, which is really impressive.

Have you used ovirt? It's currently being maintained by Oracle after Red Hat gave it up.
I've been meaning to try it, but the documentation is dense and hard to get through, and I unironically find the openstack install instructions more approachable in some ways...