Radegast
Lightweight client for connecting to Second Life and OpenSim
..., this is the first version and much has changed under the hood. It has been brought up to date and only supports Windows x64 currently and is built against the .NET 5 platform. Like Radegast, it utilizes the LibreMetaverse library and now shares much of the same code as Radegast does, which should make maintaining both viewers more manageable.