We use screen sharing of music scores a lot during Zoom sessions: mostly they are pdfs, but JPEG’s can also be shared, as can music files or videos. There is a wee arrow next to the share screen button, with a pop-up menu, where the host can find the permission to allow other participants to screenshare, so if this is enabled, anyone in the meeting can do it.
One of the sessions hosted by another friend makes use of an extensive Dropbox folder: in this instance it is useful/ easier to work with 2 screens: I usually use my laptop for the main meeting screen and iPad to access the Dropbox scores.
For any presenters, I’d make a plea to not wave your arms about to emphasise what you are saying: this happened in a lecture I watched last week, and was really distracting, especially as the movements were very “choppy” when combined with a less than perfect signal.