The PC has multiple monitors, a full-sized keyboard, and support for many windows on the screen, which makes it much easier to get work done while on a call, while the iPad is very convenient for drawing diagrams, etc. when on a call, much more so than the built in whiteboard.
So, she hosts the call on her computer so that she can do all of the multitasking she needs to during the meeting, and she connects her iPad so that she can draw and comment on precise diagrams in a way that isn’t really possible without the iPad.
From another comment it seems like she might just be missing the feature that’s usually there, but I wanted to be prepared with alternatives when I got home this evening just in case so that she’d be ready for work tomorrow no matter what.
Edit: See the OP - this is not the case. This is a proprietary function that is only available in the Mac and Windows version of Zoom, so it’s not present in the Linux version at all.
Now that I’ve gotten home and played with it a bit, unfortunately, remote/presentation mode isn’t what she’s looking for, because it doesn’t work with her iPad Notes app the way she needs it to. It shows the entire iPad screen no matter what, instead of the portion she’s using for drawing/notes.
It turns out that on the Mac and Windows versions of Zoom, there’s an option in Advanced Settings that is specifically connecting an iPad through AirPlay. Unfortunately, as I’ve found out, this is a proprietary setting only allowed on the Mac and Windows versions, and specifically excluded from the Linux version. There’s just a blank space where the option usually would be.
Luckily, the notes app function she needs does work when using UxPlay, so that’s what we ultimately decided to go with, even though it’s a bit clunkier and laggier than connecting directly through Zoom.
Thanks for the help!