I just had to edit a Google Doc for a university thing, and I found the mobile UI to be rather nice. The desktop UI, too, was very good, and I remember having good experiences with Google Slides before I began my privacy journey.
I am fully capable of using things like LibreOffice and ONLYOFFICE, and I currently just use Markdown and CSV for my documents and spreadsheets.
However, if there’s a FOSS and privacy respecting piece of software out there with a similar UI/UX to Google Docs/Slides/Sheets, I would would be very happy to hear about it.
German center for digital sovereignty (ZenDiS) is working on an office solution for the German administration called Open Desk.
If you are already using MD, perhaps you like to try Obsidian.
Obsidian is proprietary, but I’ll look into Open Desk.
Joplin is a decent FOSS alternative to Obsidian