Do you have 2 minutes a day to devote to sight-singing? If so this approach could work well for you, even if your students are remote.
When I began teaching high school more than two decades ago, “daily” sight-singing consisted of me scurrying to my chalkboard ten minutes before the first chorus class of the day to get out my prized five-pronged chalk holder so I could draw 5 poorly angled staff lines across the dusty chalkboard. Next, I would improvise an 8 measure sight-singing example and pray that I didn’t make any errors because there was no way to erase the notes without erasing the lines.
One sight-singing example a day, at best, was all I could place on the board, leaving a small area for daily announcements. I would keep the same exercise on the board for each choir, regardless of their age and skill level…