The LineageOS 16 introducing Android Pie experience is now live for the older LG G2 smartphones that were considered as a classic upon its release by the user community. If you still manage to possess the LG G2, then you could download the LineageOS 16 custom ROM.
As per XDA Developers, the LineageOS 16 is currently applicable for the LG G2 smartphones bearing model numbers D802, D803, along with the D801 and D800 versions as well. You could manually obtain the LineageOS 16 for these models from here [1,2,3,4] respectively via the official LineageOS download portal.
The LG G2, which is undoubtedly an older smartphone comes with key technical specifications - which are still worth taking a look at this juncture (due to the availability of the LineageOS 16), and you could get a fair idea of what to expect from the Android Pie experience in sync with the hardware offered by the smartphone:
In related updates, the LineageOS 16 nightly builds also recently reached the relatively old Google Pixel and Pixel XL smartphones. If you are new here, then it is worth noting that like that for the LG G2, LineageOS 16 introduces the key Android Pie experiences to Pixel XL, Pixel handsets, and these are Digital Wellbeing, improved gestures, and the newest Recents Menu, among other enhancements. Click here (for Pixel XL), and here (for Pixel) to download these nightly builds.