Add the nfsdctl tool to nfs-utils and use it to control nfsd startup and shutdown. The upstream nfsd community has a long-term goal to deprecate the nfsdfs interfaces for controlling nfsd. The new tool for doing this is nfsdctl:

https://lore.kernel.org/linux-nfs/20240722-nfsdctl-v6-0-1b9d63710eb5@kernel.org/

The corresponding kernel patches went upstream in v6.9 and v6.10. Let me know if you need help with backporting those.