Allow me to suggest build2 (the build system part) as another alternative. You would probably be first interested in ad hoc recipes: https://build2.org/release/0.13.0.xhtml#adhoc-recipe
The one thing that I'm currently struggling to find information on is dynamic dependency handling (dyndep in ninja terms).
Is that something that build2 covers as well? Any resource you could point me to?
Would it be appropriate to open a github issue for discussing this further? I would like to share some example for how my current setup is working and having the github syntax available would be helpful.