[Honor 4x ROMs, Kernels, Recoveries, & Other Develo] pndwal:
Unfortunately there is no site officially hosting older LOS builds, which is disappointing, so your chances are slim.

However, I think you'll benefit from the following info I posted previously in Aug 2018 in Ascend Y550 thread - https://xdaforums.com/android/help/to-root-huawei-y500-t2923318/page607 Post #6062 - (this is a similar 1GB RAM device with unofficial support for LOS 14.1 cherry ROM) regarding...

How Android Go Can Help Older Android Phones Run Android 8.1 Oreo

"Android Go is Google’s stripped down version of Android based on Android 8.1 Oreo, and it aims to be an optimized version of Android for low-end devices with 1GBs of RAM or lower..."

https://www.xda-developers.com/android-go-old-android-8-1-oreo/

And how to...

Turn any Android 8.1 Oreo ROM into an Android Go-Optimized Version

"Android Go is a special version of Android 8.1 Oreo that is optimized to run on low-end hardware. It consists of a series of build configurations and optimized applications that allow for owners of newer budget devices to enjoy features in the Android Oreo framework without spending more on a mid-range or flagship device. We previously outlined how older low-end devices running a custom Android 8.1 Oreo ROM might be able to take advantage of Android Go-specific optimizations..."

https://www.xda-developers.com/android-oreo-android-go-low-ram-patcher/

Looks like with LineageOS 15.1 (Android 8.1), you can turn the OS (in fact any Android 8.1 Oreo ROM) into an Android Go-Optimized version (ie downgrade to Android Go-Optimized version) if that's your wish, simply by flashing Low RAM Property Patcher from link in XDA article above, or developers thread here:

https://xdaforums.com/android/software-hacking/mod-low-ram-property-patcher-android-t3737373

Or Magisk module here:

https://xdaforums.com/apps/magisk/magisk-module-low-ram-property-patcher-t3740199

Additional info:

"Developers should get less requests to compile with or without Go just because one user wants to have a feature (multitasking for example) re-enabled or to force low-ram changes."

"The target system is Oreo, but the low-ram property was introduced since Android KitKat 4.4, therefore it should work on other versions, unless the ROM developers did not validate the low-RAM UI changes (recent apps UI mostly) against the additions they made."

"Features affected by the low-ram property: Flat recent / multitasking UI,

multi-users disabled, high-end graphics disabled, less recent apps cache,

multi-windows disabled, minor notification icons changes, less logger buffer sizes (devs), no apps notifications access / zen access / VR listeners / picture in picture (PIP) accesses."

I ran Magisk module, and low-ram property flag had the expected effect (with LOS14.1). Of course, in playstore this will not invoke "Go" optimised apps automatically unless running an Oreo ROM. However these streamlined / light apps are already available from 'Comparable app available' notice. [Eg. selecting Maps (Google) notifies you that Google Maps Go is available as Comparable app]. This makes it possible to manually achieve most of the 'Go' optimisations without Oreo (Ie. by flagging the low-ram property to adjust / disable the 'higher-end' features listed above, and by swapping out standard apps for Go edition apps)

I strongly recommend trying Low RAM Property Patcher to invoke Android Go-Optimized OS on any Oreo or Pie device with only 1GB RAM as these android OSs are otherwise far more resource hungry than versions up to Nougat. Hope it helps, PW.