certain reading materials are only available in djvu format and converting them to pdf increases used disk space (or djvu files are lighter).
a djvu.js integration, like pdfjs could be useful for reading files (also, many platforms doesn’t have native/easy option for reading djvu files - having it in obsidian helps lot)
djvu.js https://djvu.js.org/ is a react based for handling djvu files. It could be integrated (along with) as pdfjs.
djvujs works fine in safari also. Currently there is no way to embed/open djvu files in obsidian.