Custom rom LineageOS 17.1 seems to be coming for the Google Pixel 2, Pixel 3a and Pixel 4. A stable version of LineageOS 16.0 was recently released for the Pixel 2 phones for the first time. Google support for the Pixel 2 series will end soon.
The release of LineageOS 17.1 for the Pixel 2, 3a and 4 appears imminent, a Redditor noted in the documentation on upcoming phone support. The 2016 Pixel 1 and 2018 Pixel 3 already had support, so with the 2017 Pixel 2, 2019 Pixel 3a and 2019 Pixel 4 support is complete for non-current models from the manufacturer.
Especially for the Pixel 2 series that support is on time, because Google provides updates and upgrades for three years and that model came out in the fall of 2017. According to the search giant, support will run until October of this year. The Pixel 3a and 4 will receive updates and upgrades through 2022.
It is still unknown when the official versions based on LineageOS 17.1 should be released. LineageOS is the best known and probably most used custom rom on Android. The most recent version was released in April.