You won't have a music/band sub. Your real non-playing options are busywork (read: theory worksheets) or study hall.

And if you leave busywork, it either will get done badly or won't get done at all.

Personally, I'd just put a couple assignments on your LMS (Google Classroom, Blackboard, etc) for online playoffs and say "These are due February 13 by the end of the class period." (Yes, the day you come back). If you use FlipGrid it's even easier.

If you haven't been making these a part of your daily rehearsal process since we went back to in-person learning, do your choice of busywork or study hall. Don't expect your kids to know how to use programs that you haven't used in years.