I had hoped writing browser-based apps would let me put old phones to productive use, but the effort-to-reward ratio is really bad for my old Windows Phone 8.1 devices. After a short investigation, I will treat WP8.1 as a separate platform with their own (TBD) project focused just on the capability they have. I'm not going to worry about that platform for general-use browser apps like my AS7341 web app. Does this decision also rule out Android phones of similar vintage? I was surprised to learn the answer is "Not Really." It appears Google keeps Chrome updated for Android phones well after they stopped receiving Android updates.

My data point for this investigation was my Nexus 5 phone, which was my personal successor to my Lumia 920 Windows Phone. The hardware is old enough its battery degraded enough to start puffing up. That was replaced with a buck converter pretending to be its battery so I could continue using the device. I powered it up to answer the question: how out-of-date is the Chrome browser on this thing? After updating everything available from Google Play store, I tapped on "About Chrome" and was amazed to see version 106.0.5249.126 which was released October 13th 2022.

For context, Nexus 5 launched in 2013 with Android 4. It received next two major Android updates and now runs Android 6, which stopped receiving updates in 2017. Due to this fact I had expected Chrome version to date back to a similar timeframe. Contrary to my expectations, Google continued to update Chrome for Android 6 even though the operating system itself stopped receiving updates, continuing five more years all the way to late 2022. But Chrome 106 was the end of the line, my Nexus 5 could not pick up 107.0.5304.54 released a week and a half later on October 25th, 2022. (Annoyingly, this meant Chrome 106 would display a "Chrome update now available!" prompt even though this phone can't get Chrome 107.)

Looking around for a definitive resource on Chrome support, I found the "Chrome browser system requirements" page. Today it says the minimum Android version is Android 7, which is consistent with my Android 6 phone being left out. Android 7 received its final system update October 2019 yet is still receiving updates to its Chrome browser. This story of Chrome updates far surpassed my expectations and puts my Nexus 5 phone in a far better position than my Lumia 920 phone. Having a 2022-era browser should mean it can run my AS7341 interactive web app with no special treatment at all.

Unknown: Does Apple continue to update Safari for old iOS devices even if they have stopped receiving iOS updates? In a quick web search, I found no information one way or another and I do not have an end-of-life iOS device to check Safari version numbers firsthand.