[KronisLV]

> I‘d like a well-supported mainstream distro for lightweight, high performance servers. Think NGINX, routers, local web proxies, that kind of thing.

This might be a shot in the dark, but wouldn't Alpine Linux be a good general purpose candidate for this: https://www.alpinelinux.org/about/

Many use it as a basis for container images, but it also runs pretty well as a regular Linux distro, albeit musl and busybox might present some compatibility challenges in some cases. Regardless, it seems to be pretty lightweight and widely supported, most software that you'd expect is also available and generally there are few surprises.

It does have a somewhat short release lifecycle, though: https://endoflife.date/alpine