Some districts are choosing to ignore this recommendation - but in mine, no band and no choir indoors until we're told otherwise by the district. We even have to take 5 minute breaks every 30 minutes while playing outside, and completely clear the area where we were playing for that 5 minutes.
We just practice outside behind the school. It's getting cooler in the mornings, but we can live with it for now. Once it's 40-50 degrees for a high, we'll need a better solution, but by then we may even be back on full virtual school given how the numbers are climbing again.