

My distro is based on MUSL. I seem to remember finding something that would not build on it but I do not recall what that is. In addition to the thousands of packages I am using, I have compiled hundreds of applications. Compatibility is very high.
Certainly it is clear the “most applications” work with MUSL.
That is, the source code does.
gcompat is when you want to run something that is already a binary that wants to call into Glibc. I try to avoid that so I cannot comment much.
There is the odd time I have had a binary built for Glibc that I could not avoid. For example, bootstrapping .NET or the version of vcpkg that the Ladybird browser uses in its build system. To be honest, in those cases, I just reach for Distrobox and drop into a distro that has Glibc natively, like Arch. Or I might use a RHEL Distrobox for a commercial binary meant to target that distro.
Clearly running a binary without one of the dependencies it was built against is a problem no matter what library you are taking about. But if we are just asking what works on MUSL, I would say almost everything.



The default allocator is very slow but it can be changed. Chimera Linux, for example, uses mimalloc which is very fast.