When you do finally outgrow Make you should be looking at Bazel or similarly full build system.
Creating Make with YAML syntax is strictly worse than Make and yet this has to be the most popular style of "new build systems" I am seeing recently and it really does confuse the shit out of me.
EDIT: Realized this is Show HN so here is some constructive critisism. If this is a learning exercise on how to build graph style build execution systems then carry on. If however you think this is needed I think you should invest some time learning from Bazel and other new generation build systems. Ideally take some large multi-project builds and try converting them between this tool and Bazel and see if you can understand what is different paying close attention to cachability, parallelism and repeatability. That last one, repeatability is actually what makes Bazel stand out from most of it's competitors so it's worth understanding why it values it so highly when it clearly has a very high cost.