LibreOffice has both of those, provided by Collabora (the main corporate developer of LibreOffice).
For those who don't know: it renders the whole LibreOffice interface on server and passes it to you. Lots of issues with hotkeys on non-standard layouts (I use Dvorak), with language switching, with mouse behavior, with clipboard, ugh. Of course it is hungry for resources. No. This isn't the way.
I wouldn't be too surprised if their web version was like that (given how long ago the first version came out), except Nextcloud uses a Collabora-based system for its online editing, and I doubt they'd go with something like that.
There are online ODT editors (e.g. https://webodf.org/demo/ci/wodotexteditor-0.5.9/localeditor....), so even if Collabora's is bad, it wouldn't be too hard to make a better one.