question about writing parallel and group handling

I'm using the tensorstore C++ API to write a Zarr file, and I need to address these two issue in my code:
1- I want to create a group like Zarr Python and create a hierarchy of namespace and datasets. Right now, I'm handling it using kvstore path while creating them. What is the optimal way? This approach takes more time than the Python version!

2- I'm trying to write data into each chunk parallelly. I wanted to avoid multithreading for now and use mpi instead. I'm writing everything from scratch for this purpose as I couldn't find anything in the documentation. Is there any better way to avoid multithreading?

Thanks