From the scripting API reference, it looks like Sansar is using the Mono runtime, which is fine. However, it includes several references to types that are not part of the .NET standard and are Mono runtime specific.
For instance, Mono.SIMD is in the list. Going forward, the future of Mon specific APIs is maybe questionable, as everything is moving towards targeting the .NET Standard API surface (including Mono).
Before too many user scripts are written referencing these deprecated APIs (or code in Sansar itself), I'd strongly recommend targeting the .NET Standard API surface, or a subset. This would go a long way to future proof users' scripts on future versions of the Mono runtime, and gives you flexibility in choosing alternative runtimes, like CoreCLR.
FYI, in .NET Standard, System.Numerics takes the place of basic SIMD accelerated vector math. It's not as general purpose as Mono.SIMD. However, it looks like there's some discussion about adding lower level intrinsics here: