This is the reason I love ebooks on a proper workstation with a huge monitor. I can fit eight or more books open at once... but more likely 3 or 4 plus a web-browser and notes.

I might have three copies of the same book open at once. One for linear reading, one for search and one for cross referencing. Much better than a physical book. A bookmarks side-bar works well in e-readers if there are specific locations you regularly need access to.

Tablets and physical e-readers suck in comparison to a proper computer. You also might need to strip DRM to get out of some walled-garden reader that prevents you opening multiple instances of the same book. Copy paste is a killer feature for note taking (and another reason to ditch ecosystem readers that interfere with copy paste like Apple books).