That’s correct – it’s literally one of the links I posted – my concern with that is that we’re mixing two distinct workflows/use cases and exposing them via the same mechanism. 
Poetry, Hatch and PDM have dependency groups (or equivalents) because their users do not want to expose their test dependencies and whatnot to their end users. From what I can tell, there’s two groups here: (1) that doesn’t care and sees this as unnecesary (like @ketozhang) and (2) that really like this separation and want it from their tools.
I do think we’ve established time and time again that the broader community wants a more “concentrated” story around these things (eg: When you kick the packaging hornet's nest on Twitter, the hornets seem to want an opinionated, KISS solution).