libreoffice --headless --convert-to pdf mydocument.odt
Libreoffice will import a vast array of document formats and its a great tool.
For rapid viewing and searching of static documents this process is relatively slow.
An app that will grab selected formats and output them to selected formats odt, pdf…
The PDF viewer in Nextcloud is extremely rapid, but also MS Office documents might benefit from conversion to .odt.
Being able to mark a folder or file for conversion or have default conversion schemes in place.
Might even just be to convert to a common format for all and again might need something like shadow copies to increase interoperability.