With the parent comment example, all you need is nginx, available as a package on all distros, and a single static config file. With an auto-updating package manager and a service manager, one never needs to write anything else apart from that static config file.
Or did you mean something else with "actually maintainable"?
So that's not a problem. Besides the majority of nginx setups don't rely on too fancy things; most of the stuff that gets changed in updates that affect config files are the fancier nginx modules.
If you're following that approach then having auto updates enabled is kind of irrelevant/meaningless; at some point you're going to be running a very old (and unsupported) version of your distro with all that that implies.
Maybe. I have more faith in a Rust library to maintain API backward compatibility than a Linux distro, is what I'm saying.