Sandstorm.io is Docs-like in it's collaboration features. But the OP specifically discussed offline operation as an important functionality, so cloud-based collaboration tools without a local application may not fly.
So I'm not sure if it's because of problems from the host of the CryptPad instance or because of CryptPad itself, but I've been using CryptPad for a collaborative spreadsheet for a weeks now, and it's been absolutely awful
- Lost modifications, a lot of times ("something went wrong, please reload" and then the last 15 minutes of changes are just GONE)
- Very frequent "synchronizing... please wait" screens that block you from doing anything for a few seconds
- Undo/redo not possible in "live editing mode"
- In "non-live editing mode", if you don't hit save manually and the TCP connection resets, you will lose all your changes
- Pivot tables do very weird things with formatting
And that's the experience of a solo user, there wasn't anyone joined in on the document at the time. I can only imagine how it would have been if were multiple persons working on that spreadsheet.
I do have a flaky Internet connection, but Google Docs handle it fine, and emacs-crdt works very well too.
I'm now refactoring the whole spreadsheet into a bunch of .csv files stored in Git, and a Python script that outputs a pivot table, because I've lost more types due to CryptPad bugs than the time it would take me to write that script.
As opposed to files that consist of a '1' in them [1], or .ds_store files [2]. Not to mention the risk of Google just decided to lock your account for no clear reason and you losing access to all of your files, like the hundreds of horror stories out there.
Not macOS here but I've crashed LibreOffice products (usually Writer) countless times on Debian by doing such things as moving/resizing line drawings, attempting to add basic charts, attempting to adjust wrap settings for images, replacing images with other images, and setting tab stops when there are things other than pure text in the flow. I can live with most of these, although they are annoying. I just wish I had a more consistent experience so that I could contribute to fixing these issues, but it doesn't seem consistent at all; once I restart the software and try the task again, it usually works relatively fine (exporting to pdf/docx for my colleagues' benefit making a mess of it notwithstanding). I've since settled on doing the bulk of the work in LibreWriter, exporting to docx, then opening in Word on a separate system to massage the appearance.
And before anyone chimes in, no, LaTeX (or Markdown, etc.) would not be appropriate for these projects due to the mental overhead I'd have myself. I'm a visual person, I need to see what it looks like as I work and adjust with immediate visual feedback, and that visual aspect is often critical to the final product.
Word is phenomenal even with the missteps and lacking bits, and I pray (ineffectually) that Microsoft will eventually makes a properly compatible version for me that isn't plagued with the issues and feature disparities the SPA web versions are.
I don't think I do, no. I'm really a fairly novice user, since I've only used Ubuntu here and there since 12.04 (I think) and not committing until 18.04, then switching to Debian Jesse with... I think it's GNOME. So basically the same thing as Ubuntu? I do wish I understood more about the underlying tech and window managers and such, because I know I could get more out of it all, but I really just follow poorly written blog tutorials for settings things up until it's "good enough". I am scared to play around much more for fear of everything becoming unusable, since that's been my experience in the past with the ALSA/Jack/PulseAudio mess and with video card drivers.
Are there open-source implementation of Docs, even poor ones?