I have the Qingping Lite[1] which is a well-made device (and can run on batteries if you want to take it somewhere to check things out). After updating the firmware and calibrating it outside it seems pretty consistent - though I was mostly interested in it for CO2, I have a Flow 2 which doesn't agree on PM2.5 or PM10 with the Qingping, I suspect that the particulate sensor in the QP is not the best, it always seems to read low.
1: https://breathesafeair.com/qingping-air-monitor-lite-review/