Can I screen-share (Mac to Mac) a mirrored iPhone over Messages?

I'd like to support my elderly mother (remote support, she's in a different country) in her use of her laptop and iPhone. I'm considering switching her (Windows) laptop to a Mac, since I know I can screen-share over Messages. Share your screen using Messages on Mac – Apple Support (AU)

I'm also aware that if I got her a Mac she would be able to screen-mirror her iPhone on to the Mac's screen. Use AirPlay to stream video or mirror the screen of your iPhone or iPad – Apple Support (AU)

My specific question: if she shares her Mac screen with me over Messages, will I be able to see (and control) her iPhone if she screen-mirrors it to her Mac?

If not, my broader question is whether there is some other way I can help her with her iPhone remotely? (telling her how to control it isn't working, I have to be able to see and interact with her phone directly).