I tried it on https://github.com/monkeytypegame/monkeytype and it just said ESLint and Prettier which doesn't describe much. It probably would work properly if it worked recursively or at least checked the first directories. I like the website and api option though.

I cannot say I have had the experience you describe. Most repos describe their stack clearly, or you can figure it out easily enough. Is it really a common problem for you?