Following up on @keats’ suggestion that I could post a custom build of Zola somewhere and use that to drive my Netlify builds turned out to be rather more complicated than I initially expected.
I did ultimately get it to work and the process is longer than I feel comfortable sharing in a forum post.
If you’re interested, there’s a recipe on my new, Zola-based dev blog: ericscouten.dev: Deploying a Custom Build of Zola to Netlify.
Hope this helps!