I had this exact problem a whole ago, trying to find an alternative to OneNote. I went through many of the other suggestions in this thread but settled on Trilium.

Super easy to setup in a docker container. Self hosted so I control my data and access. Can by accessed via reverse proxy when I’m out and about.

Notes can be a mixture of text, pictures, code (with formatting based on language)

They are arranged in a directory structure with notes inside other notes under chosen topics down the left, and open notes are in tabs along the top, much like One Note.

The chrome extension allows me to quickly snip and send back screenshots or Urls of sites I’m on, and the android app let’s me make quick notes which are filed away by date for later organisation (when I get round to it…)

The only thing it doesnt support, that I wish it did, is multiple users. I don’t see why you couldn’t just make another container for each user, just not very practical if you have a lot of users.