If Scheme/Racket people are feeling inspired, you could look at two that I made, and make something with different properties, informed by Spinneret:

* Static syntax-based: https://docs.racket-lang.org/html-template/

* Dynamic data-based: https://docs.racket-lang.org/html-writing/

I like that Spinneret focuses on HTML5. My work started over 20 years ago, with HTML always being quirky, and also sometimes used in conjunction with my permissive HTML parser. So there's a need to maintain backward-compatibility with how things worked before, including weird non-open-source things. (With the parser, I've also recently gotten requests to support 20yo HTML, for dealing with legacy data.) Doing something all new, tailored to HTML5 or something higher-level, would be able to do some things better. (But I strongly recommend trying to stick with SXML representation/syntax at some level, though, since it's a de-facto standard in the Scheme world, and can be used in a way compatible with representing HTML5.)