LibreOffice needs to pull their heads out of the sand and recognize that both OOXML and ODF are the past.
Make it a polyglot ZIP à la SingleFileZ if you have to (or polyglot JSON[1] or just straight up XHTML with a big sidecar blob of embedded metadata), but nothing trying to take on Microsoft Office is "the future" if it's trying to get there with a strategy shackled to the notion of people downloading the appropriate format-compatible software for something as simple as being able to view (not even edit!) the document that has been sent to them.
It's great to have open standards and free software, but be compatible by default with the universal formats understood by the readers for the ubiquitous document infrastructure that everyone already has installed (WHATWG-/W3C-compatible hypertext readers, i.e. Web browsers), or be forever doomed to the same level of obscurity that OpenOffice/LibreOffice were fated 10–15 years ago due to their myopia.
> A forward-looking format is one that reduces future dependency, not one that reinforces it[…] A “backward-looking” format, by contrast, is one that ties the future to the commercial strategies of a single vendor. In this sense, OOXML Transitional is an archaeological artefact that preserves the past at the expense of the future.
This is delusional. As long as it's modeled on the same outdated paradigm of 80s- and 90s-style office suites (no matter which one), then any format whether it's an ISO standard or not is hopelessly attempting to preserve the past.
I hope that Germany mandating ODF over OOXML will enhance the whole ecosystem.
As a programmer, finding decent ODF libraries is far from certain. Last year I had to output some spreadsheets from a Go program, but I could not find any maintained library for ODS, so I had to output XLSX files. Recently, I was luckier while programming in Rust.