> GOGC was introduced in Go 1.5

yes, that's quite literally what I meant by "GOGC has always been there". 1.5 was released 10 years ago, just 3 years after 1.0.

So to summarize: there is one knob (that has been there from basically the beginning), plus a second one (if you squint hard enough: GOMAXMEM), and absolutely no plans to add further ones, or to add alternative GCs.

That would be since Go exists, literally.