> You can roll stackful coroutines in C++ (or C) with 50-ish lines of Assembly

I'm not normally keen to "well actually" people with the C standard, but .. if you're writing in assembly, you're not writing in C. And the obvious consequence is that it stops being portable. Minicoro only supports three architectures. Granted, those are the three most popular ones, but other architectures exist.

(just double checked and it doesn't do Windows/ARM, for example. Not that I'm expecting Microsoft to ship full conformance for C++23 any time soon, but they have at least some of it)

There is no "Linux/ARM[64]". But there are "Raspberry Pi" and "RISC-V". I don't know such OSes, to be honest :-)

This support table is complete mess. And saying "most platforms are supported" is too optimistic or even cocky.

Boost has stackful coroutines. They also used to be in posix (makecontext).

I think what they meant is that that what it takes to add coroutines support to a C/++ program. Adding it to, say, Java or C# is much more involved.