Another project is OdpDown. It converts Markdown to Opendocument Format presentations in contrast to the PDF that is created by Marp.
I like the approach of creating a single static file (i.e. no JavaScript).
An advantage of creating ODP files is that the whole reusable presentation is one file. PDF is not as friendly for reuse. The presentation author that uses Marp could publish a git repo or a zip file with the source files.
A big advantage of HTML and PDF is that they render directly in the browser. ODF support in browser is a still a dream for the future.
The author of odpdown is a contributor to LibreOffice.