Awair seems to be the best-known consumer brand (?). I use an Awair Element which works great and has no subscription fee for the associated app or local API functionality, so it doesn't seem like it could be them?
In the United States, AirNow.gov includes most PurpleAir sensors, although they are annotated differently than “higher quality” sensors (I was going to say than government sensors, but here in Connecticut, the state has a number of PurpleAir monitors deployed and rapidly deployed more when stuff got bad due to Canadian wildfires a few weeks ago).
Fortunately, for local users, you can hit your own sensor and grab the data however often you want. I even wrote a tool to help out and drop it into influxdb and post it to MQTT[1]. They still support local fetching of data. However, many default integrations from tools like Home Assistant could be affected as they use the cloud integration.
https://www.reddit.com/r/Awair/comments/y7i5ku/awair_discont...
Unfortunate that older devices didn't get it, but at least they're following future-proof best practices going forward.
My biggest complaint with Awair is they only let you download the last month of data easily from the app. That said, they are hacker-friendly otherwise -- for example they offer a local API!
That said, IQAir is kind of crazy to me. They launched a new dashboard which has a "view as TV dashboard" button, but doesn't let you click it unless you upgrade your plan. The local data access situation is also unclear to me; I bought the sensor after reading that it has a Samba server, but it requires the indoor monitor to display the password to you. I opened a support case to get the password for local analysis, but am beginning to feel like they're not going to give it to me. (Who wouldn't want an indoor air quality monitor? Well I already have one. I've cared about indoor air quality forever, but after wondering for two days why the sky was a weird shade of yellow, I wanted to keep an eye on outdoor air quality as well.)
In that case, it will be UART time. It's definitely Linux running an out-of-date unpatched Samba. Won't be at all difficult to get my data, I'm guessing. The question is... why do they think there's money in a cloud service that shows you dashboards of your own data? They should be bending over backwards to accommodate anyone that wants to contribute to their public site; they are way behind PurpleAir there.
TL;DR I'm certain that PurpleAir is the unnamed company in this article. IQAir is too new to be relevant in the space.
Ignoring the software, the device itself is great. Two sensors compare their outputs to figure out if it's valid or not, and the case seems quite protective from the elements (and easily mounted to my weather station pole). I didn't need POE, I have AC out there, but overall it's a good way of supplying power to something like this.