maybe this optimization is generalizable?

if (typeof(T) == typeof(double) && Vector256.IsHardwareAccelerated)
{
    var _this = Vector256.Create(
        Unsafe.As<T, double>(ref Unsafe.AsRef(X)),
        Unsafe.As<T, double>(ref Unsafe.AsRef(Y)), 
        Unsafe.As<T, double>(ref Unsafe.AsRef(Z)), 
        0);
    
    var _other = Vector256.Create(
        Unsafe.As<T, double>(ref Unsafe.AsRef(other.X)),
        Unsafe.As<T, double>(ref Unsafe.AsRef(other.Y)), 
        Unsafe.As<T, double>(ref Unsafe.AsRef(other.Z)), 
        0);

    return _this.Equals(_other);
}

if (typeof(T) == typeof(double) && Vector256.IsHardwareAccelerated)
{
    var _this = Vector256.Create(
        Unsafe.As<T, double>(ref Unsafe.AsRef(X)),
        Unsafe.As<T, double>(ref Unsafe.AsRef(Y)), 
        Unsafe.As<T, double>(ref Unsafe.AsRef(Z)), 
        0);
    
    var _other = Vector256.Create(
        Unsafe.As<T, double>(ref Unsafe.AsRef(other.X)),
        Unsafe.As<T, double>(ref Unsafe.AsRef(other.Y)), 
        Unsafe.As<T, double>(ref Unsafe.AsRef(other.Z)), 
        0);

    return _this.Equals(_other);
}

        if (!RuntimeHelpers.IsReferenceOrContainsReferences<T>())
        {
            var size = Unsafe.SizeOf<T>();

            if (Vector128.IsHardwareAccelerated && (size * Count) < 16)
            {
                Span<byte> data = stackalloc byte[32];
                data.Clear(); // optional?

                var copy = this; // make you guys happy
                MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref copy, 1)).CopyTo(data);
                MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref other, 1)).CopyTo(data[16..]);
                
                MemoryMarshal.Cast<byte, Vector128<>()
            }
        }

        if (!RuntimeHelpers.IsReferenceOrContainsReferences<T>())
        {
            var size = Unsafe.SizeOf<T>();

            if (Vector128.IsHardwareAccelerated && (size * Count) < 16)
            {
                Span<byte> data = stackalloc byte[32];
                data.Clear(); // optional?

                var copy = this; // make you guys happy
                MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref copy, 1)).CopyTo(data);
                MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref other, 1)).CopyTo(data[16..]);
                
                MemoryMarshal.Cast<byte, Vector128<>()
            }
        }