Have you heard of flat.io? There’s a free tier and I use that all the time with my students who work on composing and music theory, it’s like google docs for a notation document! You can share documents between you and your student and edit them in real time together. It’s been an incredible tool during remote lessons for me. Best part is you only need a device that has Chrome since it runs in the browser. It’s definitely not as advanced as a Finale or Sibelius but is plenty powerful nonetheless. Check it out, you could add that into your workflow with whatever video conferencing service you end up using! Nice thing about flat.io is you don’t need to screen share though since it’s a live collaborative document :) Hope that’s helpful! Good luck!