LineageOS 19: Google's Pixel 2 and 3 other iconic old phones getting Android 12
1. OnePlus 6 (and 6T)
The OnePlus 6 and 6T were launched when OnePlus was still one of very few manufacturers making flagship killers. Both the OnePlus 6 and 6T were pretty well received by users and reviewers — aside from the display notches, that is — and featured premium build quality, great performance, and a no-frills Android experience thanks to OxygenOS. OnePlus also just recently ceased support for the OnePlus 6 series after three major Android updates, leaving them both on Android 11 — actually not a bad run, all things considered.
If you're happy with the camera performance of the OnePlus 6 or 6T, and one of them is still filling your pocket, there are very few reasons why you shouldn't use LineageOS to upgrade it to Android 12 and keep on keeping on (OnePlus 6 ROM and guide; OnePlus 6T ROM and guide).
2. Xiaomi Mi A2 (Mi 6X)
One of the perks of the now-defunct Android One program was supposed to be that phones in the program received longer than normal support and had a mostly stock Android experience. In the case of the Xiaomi Mi A2, at least one of those was true. Xiaomi sadly abandoned the Mi A2 with Android 10.
The Mi A2 launched with the Qualcomm Snapdragon 660 SoC — not a particularly performant chipset, even for 2018 — although it still manages to more or less keep pace with the Mediatek Helio G35 in the 2021 Nokia G20.
3. Google Pixel 2 and 2 XL
Between the reasonable price, premium materials, and unique design, the Google Pixel 2 and 2 XL were fan favourites among Pixel users. The strong camera and SoC performance made the phone stick around in the pockets of those of us who are not eager to upgrade unnecessarily.
Unfortunately, Google cut off support for the Pixel 2 series before Android 12 launched. That means if you want the fancy new Material Design tweaks or privacy bells and whistles, LineageOS and the custom ROM community are your only options. You can download the official LineageOS 19.1 builds and follow the installation guides for the Pixel 2 (guide) and 2XL (guide) on LineageOS.org.
4. Pocophone F1 (Poco F1)
Xiaomi launched the Pocophone F1 in 2018 at an extraordinarily low price, pitching the device as another flagship killer. While the results were mixed — with the F1 suffering in many camera tests — the device did feature a Qualcomm Snapdragon 845 SoC and 6 or 8 GB of RAM, meaning performance should hold up to almost all daily tasks except for some heavy GPU loads.
This iconic device was one of the first in the midrange wars that led to the rise of brilliant devices like the Samsung Galaxy S10e and more recently the Galaxy S21 FE, not to mention everything that has come out of Poco in recent years.
XDA Developers has a full list of devices with official LineageOS 19 Android 12 ROMs that you can peruse if you are interested in diving into the world of non-stock Android. Beware of unofficial ROMs — though they may not cause any problems at all, you are putting your trust entirely in the developer of that ROM, and you can never know who to trust. Before you take any drastic measures, it's worth checking an Android 12 update tracker to make sure your manufacturer hasn't released or planned an update already.