Page Comparison

https://pierasystems.com/products/piera-7100-intelligent-particle-sensor/

only $100 and unlikely to give the performance we need but does claim to give particle size histogram

https://www.plantower.com/en/products_33/74.html

https://pubs.acs.org/doi/epdf/10.1021/acs.estlett.3c00030 - does better (allegedly) than IPS-7100 at <1 micron

*has been found to not always adhere to manufacturer guarantees

https://temtopus.com/collections/handheld-particle-counter-1/products/temtop-pmd-331-handheld-particle-counter-dust-monitor-air-quality-monitor-dust-meter-laser-particle-sensor-for-pm0-3-pm0-5-pm0-7-pm1-pm2-5-pm5-pm10?variant=40680606466096

Goes below 1 micron, is designed to be handheld, well-regarded

https://www.aqmd.gov/aq-spec/sensordetail/piera-systems---can%C4%81ree-r1

IPS-7100 but able to detect at a larger field

https://www.aqmd.gov/aq-spec/sensordetail/purpleair-pa-ii

Best coefficient of determination found so far, used by Forest Service