Pis are actually pretty terrible at running a NAS. Sure there are people who do it and create content about it (Jeff Geerling) and that's kind of the schtick - it's quirky and weird and has some sharp edges. Great for making content or going down rabbit holes, not so great for actually running a high availability system that just works with minimal fussing.

There are a ton of very capable x86 systems that are small and accomplish the task at great power and noise levels.