I hooked up a PM2.5 sensor[1] I ordered during wildfires a few years ago, and the EPA's AirNow has been far more consistent with what I'm measuring than Purple Air or IQAir.
Accuweather and Windy.com have pretty good forecasts, but the ones that have been the most accurate this week for me are the US Forest Service's BlueSky models.
[1] Plantower PMS7003 are less than $20 on AliExpress. Here's a quick plot of the data https://i.imgur.com/FjABgpP.png including a spike where it was above a grill.