And then you will get at most three upgrades!

At the 6+, it looks like it's at 5 years (or more). https://support.google.com/pixelphone/answer/4457705?hl=en

What I’m seeing on that page seems to indicate that the Pixel 6 will receive Android version updates for 3 years after its release, and security updates for 5 years.

provided your phone doesn't bootloop or otherwise have the hardware fail. Android phones - from google in particular - are notorious for this. Should things fail, you're screwed.

That’s security updates only not operating system updates,

For reference, Apple just released a security update for the 5s from 2013 this past June.

The 6S (2015) ran the latest OS until ios 16 this year.

It looks like the oldest phone with current support is from 2019. The 2017 iPhone is still getting OS updates. And up until September this year, the iPhone from 2015 was still on the current OS. Does any Android phone even get half long of a software update cycle?

iOS 12.5.6 was released in August to address a security vuln for the 5s, 6, etc.

The 5s debuted Sept 2013 as the first 64-bit phone, and the first phone with a Secure Enclave, so I'm kind of hopeful they'll just keep limping it along forever for good will... I own a pair of them and adore them dearly.

On the topic of iOS, be sure to check out https://libimobiledevice.org/, which provides utilities like ifuse that will even get you access to your Photos sqlite database; including all the machine generated tags, aesthetics scores and such.

Since around 2011, Apple has allowed you to download the “last compatible version” of apps from the App Store.

As of 2019 at least, I was able to reset my first ten iPad (2010) and redownload and use Netflix, Hulu, Crackle, Apple’s iWork suite, Spotify and play music that I had previously purchased from iTunes.