I have spent hours trying to perfect build.prop and when I finally was at the end I forgot about this leakage. Any app can easily know device's bootloader info. I realized this when I ran CPU-Z. Installed Magisk and Xposed in systemless mode. Running Lineage OS 14.1. I by no means an expert as it is clearly evident from my question otherwise.
Idea is to hide or fake this information from any app including system apps. But I am failing miserably at achieving this since I have no deep understanding of Android.
I searched Git and XDA but answers were not met with requirement. Final search with keywords "getprop ro.bootloader" shade some light about the fundamental commands about getting this info. I am exhausted right now and I might be not thinking in the right direction so your input matters a lot.
I await your instructions!