For ~100K authors with content on Github Pages, Liquid conformance avoids learning new template syntax or a programming language.

For a greenfield site where Jekyll/Liquid compatibility is not beneficial, Zola may be an option, https://github.com/getzola/zola

One key feature of Liquid is that you can safely run customer-written code on your servers without worrying about security. It's a very underpowered language by design. This means that it's rather easy to be confident that its sandbox isn't leaky.

Looks like this does compile time templating. There are reasons to explore using those over runtime templating but they don't cover all of the use cases.