There are different levels of cleanroom, and ISO9 is roughly as clean as regular indoor air. I don't see anybody talking about what class their cleanroom was rated following inspection, nor do I see any indicator as to what the regulations will ultimately require.
Obviously it needs to be a room that is clean, with easily sanitizable surfaces - floor, walls, ceiling, work surfaces in particular. It needs to not be dusty. But does it need to be less that 10,000 particles above 1 micron in a square meter? Will that be required? I feel like the term cleanroom is being thrown around without really meaning anything beyond a room that's clean. The amount of air flow and the grade of filter always get left out of the discussion, probably because there is no standard to dictate it.