This tool looks up a language code and checks whether it is enabled and can be used on MediaWiki sites, what the localization status is for various relevant message groups, and which Wikimedia sites exist in that language.
It is running on Toolforge at https://codelookup.toolforge.org/.
The tool is inspired by and backwards-engineered from SPQRobin's Codelookup tool, which stopped working some time in late 2021/early 2022, but with some added functionality.