The Samsung Galaxy S20 lineup is powered by the company’s Exynos 990 chip in all regions, except in a few countries like the US where the device packs the Qualcomm Snapdragon 865 SoC. The US Snapdragon model is traditionally impossible to bootloader-unlock, so most of the aftermarket developments are centered around the Exynos variant. This year, however, it appears that you can unofficially unlock the bootloader of a handful of Snapdragon Samsung Galaxy devices. In fact, we now have confirmation that AOSP-based custom ROMs such as LineageOS can run on the Snapdragon Galaxy S20.

Samsung Galaxy S20/S20+/S20 Ultra XDA Forums

Based on the work of XDA Recognized Developer jesec, developers jimbo77 and chongodroid have released an unofficial build of LineageOS 17.1 based on Android 10 for the Snapdragon Galaxy 20 (code-name "x1q") and Galaxy S20 Ultra (code-name "z3q"). A build for the Galaxy S20+ (code-name "y2q") isn't available just yet, since none of the contributors have access to this particular variant. If you’re interested in trying out a near-stock Android experience on your Samsung flagship, you can download the appropriate flashable ZIP file from the forum thread linked below.

Download Unofficial LineageOS 17.1 for Snapdragon Samsung Galaxy S20

Before you go ahead and flash the ROM, you’ll need to unlock your device’s bootloader and install a suitable custom recovery for these variants. If you are running One UI 3.0 beta on your Galaxy S20, you should revert back and install stable Android 10 firmware for compatibility reasons.

It is worth mentioning that the aforementioned build of LineageOS is a source-built ROM and not a Generic System Image (GSI). The ROM doesn’t come with Google apps built-in, so you’ll also have to flash a Gapps package separately if needed. Since this is an early build of LineageOS 17.1 for the Galaxy S20, it might not be stable enough to run on your daily driver. In case you encounter any bugs, you can report them by following the instructions given in the forum thread.