If you can get into the beta, the Jai programming language by Jonathan Blow ticks the box of "no build system required." With how the build system is managed (just running arbitrary code at compile-time that modifies the build process), I can do this 99% of the time:

  #run compile_to_binary("name_of_binary");
  
  main :: () {
    // ...
  }

  #import "base"; // my own library that has 'compile_to_binary'

I'll go into depth about what this does, but if you're not interested, skip to the final code snippet.

The above code '#run's any procedure at compile-time (in this case 'compile_to_binary' which is defined in the library I imported). That procedure (really a hygienic macro) configures my 'workspace' to compile down to a 'name_of_binary' executable in the current directory. Any third-party libraries I've imported will be linked against automatically as well.

To do this without a dedicated procedure, just put this in the same file as 'main':

  #run {
    options: Build_Options_During_Compile;
    options.do_output = true;
    options.output_executable_name = "name_of_binary";
    set_build_options_dc(options);
  }

  main :: () {
    print("This is all I need to build a project\n");
  }

  #import "Basic";
  #import "SDL"; // or whatever...

Then compile:

  jai above_file.jai

I've done this for projects with hundreds of files that link in SDL, BearSSL, etc.

The best part is neither of these systems are a requirement to build your project. Running the compiler against a Jai file will do everything I do with my own system (I just like having the ability to configure it in code).

Jai has been a breath of fresh air in terms of "just let me write code," so I highly recommend it if you can get in the beta.