OnlyOffice (https://www.onlyoffice.com/) is the only one that I believe comes very close to either of these. It has several components that can be used individually or together, I believe all AGPL-licensed. They have fully featured in-browser editors for documents, spreadsheets and presentations that can be used with their document management system (also very good) or integrated into Nextcloud (or similar). There's also a PMS, CRM, E-mail and calendar.

In case anyone else had difficulty finding the source code link on the web site: https://github.com/ONLYOFFICE

Some words of caution about moving away from mainstream products like Office (or Gsuite, to a certain extent). Most alternatives have today very good features, but inter-operability between platforms remain somewhat an issue. Arguably my experience of this is a bit dated (2 years) but at the time there were still issues on format conversions. It is less of a problem with .doc formats (though I found Libreoffice messing up on how these are converted to/from, for example when images where embedded between text), but if you work with spreadsheets in a meaningful way (i.e. you build heavy models and financial projections, with pivot tables etc.) can you afford to doubt whether a file will operate as intended once converted to/from xlsx when you need to share it with someone outside your team/company? Gsuite is much more basic, in terms of features, than Excel so i believe this is less of a problem.

LibreOffice online:

https://wiki.documentfoundation.org/Development/LibreOffice_...

https://www.collaboraoffice.com/code/

What about nextcloudd's office solution? I'm interested too. Thinking about giving it a try for our school network which already runs its own nextcloud instance.

Huh, nice. May I ask what school is that

If you like open office you might like the collabora code app for Nextcloud.