GitHub JennaScvl (Berry Bunny in Second Life, Kallisti#2038 on Discord) recently announced work on a Unity-based viewer for Second Life and OpenSim using LibreMetaverse. This blog post provides resources related to the development of Crystal Frost which is still at an early stage of development.
The Unity project code and resources can be obtained at https://github.com/JennaScvl/CrystalFrost
Starter scene is in Scenes/SampleScene (may be renamed in later versions).
Update: February 2023 – New World News Blog Post, 2-Feb-2023