I used to write presentation slides in Markdown using pandoc+beamer. Basic contents are written in plain Markdown, but you can always resort to LaTeX beamer for advanced features. In the end, it compiles to a PDF file.

A blog post: https://ubikium.gitlab.io/portfolio/latex-beamer-flake.html Example code: https://github.com/crvdgc/latex-beamer-flake