Today I did my first advanced spreadsheet on LibreOffice after switching to Linux, and it handled itself pretty well. I had to search for some features on the web at first, but after I got it down, I felt comfortable using it. Also, LibreOffice’s default menu layout is not pretty, but I can find all of the functions with just a click, unlike MS Office’s ribbon menu where I had to click around to find what I was looking for. Sorry for bad English.
Yes. Its the obvious choice for desktop.
But if you want web, have you tried CryptoPad.
Collabora used to offer Libre Office online, now it’s their Libre Office fork
Rollapp lets you use LibreOffice online but I don’t think there is collaboration