Chasing through to https://www.bosch-sensortec.com/products/environmental-senso...

> Discover the PurpleAir PIXEL, one of the first end devices featuring the BMV080 particulate matter sensor for precise local air quality measurement. This user-friendly device provides real-time PM2.5 readings with a quick response time, clearly displayed via LED indicators. The BMV080‘s fanless design ensures completely silent operation, making it both effective and unobtrusive.

https://www2.purpleair.com/products/purpleair-pixel

That's the form factor you'd be looking at when its included with the rest of the supporting circuitry and logic.

So... possibly might be able to get it into a smaller package if the data display is externalized (Purple Air uses LEDs).

My parents are interested in this as one of their use cases is to put it on their e-bike so that they can be made aware of worsening air conditions after they've left the house.