Wow, I hadn’t heard about this before. I like that it’s FOSS with AGPL 3. The OnlyOffice screenshots of the spreadsheet application look beautiful (compared to the ugly LibreOffice Calc ones). It says that it works with ODS files (which LibreOffice Calc uses).
Any gotchas to be aware of with OnlyOffice?
It can't handle OpenDocument files (odt, odp, ods) well. Only a one-way import is supported. https://helpcenter.onlyoffice.com/docs/userguides/document_e...
There are parts that are not released under a Free Software license but that's unclear from their marketing-communication. #openWashing
https://www.softmaker.com/en/products/softmaker-office is a thing as well, and I prefer it to Only Office. The maker is German.
It's a bit slower performance wise
Calligra (KDE Office Suite) is also pretty interesting but currently Linux-only https://calligra.org/
here is a (somewhat biased) comparison between OnlyOffice and Collabora Online
https://www.collaboraonline.com/comparing-collabora-with-onl...
"Somewhat biased" is a gross understatement here, holy crap.
https://github.com/ONLYOFFICE