XML/XSLT/XPath are great, but XSLT ecosystem has been effectively "frozen" for over a decade in terms of innovation and tooling. The last major step was XSLT 3.0 (2017), which introduced streaming and function integration. However, in practice, no new engines or radically different approaches have emerged since then.
And there is only one free XSLT 3.0 processor available, SAXON-HE (it lacks schema-aware & streaming though)