Many of the teachers in our district, especially at the secondary level, are currently using the Google Meet Attendance (Green Checkmark) extension to keep track of who is attending their Google Meet sessions.  If you have not already tried it, you might consider taking a look at the features which are highlighted in this slide deck.  The app is coded by a high school teacher from Canada in his spare time!  His latest update includes a way to keep track of students who might be "ghosting" your Google Meets by signing in with their cameras and mics off and then walking away without participating.