How can I tell if I'm making enough progress when working remotely?
Yes, you should raise this issue, both with the advisor and with the university administration. Students need some feedback on their work and it is the university's responsibility to provide a way for that to happen. They need to provide the channels and you need to find a way to use them. 

But things are in a bit of chaos now, of course, and effective response can be slow to occur. 

Virtual seminars are possible using simple or sophisticated software. Perhaps you can set up (or the university can) a group of students and a professor or two willing to have an online session regularly. It isn't the same as face to face, but it can keep you engaged. 

But at a minimum, write a lot and note where you have problems. Ask a lot of questions, but make sure they are pretty focused. Share what you write with your advisor, by email or by posting it somewhere. 

Ask your advisor directly how you are doing and ask explicitly for next steps. You will most likely get suggestions about reading. Take a lot of notes on the readings and note things that puzzle you. Ask about them. 

If you are starting the research phase of the degree it is normally a fairly solitary effort in any case, but the advisor should be willing to review and respond to your efforts and your questions.