Bit of a tangent here but what’s a pip/npm/cargo like package manager for C++? For example ‘pip install boost’? I’ve never worked it out for hobby projects and never worked with it commercially
If you control the compiler AND build system you can get away with just one package for most cases. This true for Microsoft’s C/C++ package manager, NuGet[3]
Historically, the convention has been to use the package manager of the underlying system to install packages, as there are so many different build configurations to worry about when packaging the libraries. The other advantage of using the system package manager is that dependencies (shared libraries) that are common can be shared between many applications, saving space.
[2] https://docs.conan.io/1/creating_packages/toolchains.html
Declarative build systems obfuscate so much without providing the proper debugging and error-handling capabilities.
Build systems should be imperative and type-checked. A simple script that a user can step through and observe what is happening.
Makefiles suck because they are not type-checked.
The only abstraction you need is some kind of dependency graph. But then it should be completely transparent to the user so they can easily understand it.
Perhaps Meson fits the bill for you?
Pip does not attempt to resolve dependency conflicts of already installed packages, only the ones it is currently trying to install. Nor does it try to manage the life cycle of installed packages, such as removing transitive dependencies never specified or no longer needed or create consistent environments with a lock file.
As package specifications have become better defined (rather than "whatever setup.py does") and are being better enforced (e.g. Pip will soon reject version numbers that are non-compliant) there are several attempts at writing full-fledged package managers (Rye, Huak, Pixi, etc.) and I'm sure once one of them gains critical mass it will replace Pip quickly.
And many people in the community are against it, you'll hear stuff ranging from "just use the distro package manager" to "don't use any, make it a single file library".
Personally, I'd say all hope is lost.
In my experience, most of the value of Conan is with creating packages yourself when needed. You can then self-host a Conan remote and have pre-compiled binaries ready development. Having a conan recipes repository with CI that produces binaries for each required build configuration has become a de-facto standard for projects I have worked on
For 95% of Java devs, JavaScript devs, Python devs, if it's Open Source and it isn't on Maven Central, NPM, PyPi, it might as well not exist.
The reverse is true, if you have any library or tool worth a damn, it's there.