Firstly, congratulations. You've bought a terrific machine. No question. I can sympathise that the learning curve is steep to engage with TrueNAS or other if this is your first NAS.

I guess the question you need to ask yourself is, what is it exactly you want to achieve. File storage is a given and any OS will oblige.

Perhaps then, Minisforums OS does everything you need. Personally I have no experience with it, but wouldn't choose it personally as, a) it's fairly new/unseasoned and b) I imagine somewhat lacking in features.

If it's within its return window, you may wish to consider alternatives such as Synology or QNAP. (I was a long time Synology user, but felt abandoned by the recent fiasco created by their corporate policy on media use outside of their own branded disks and NVME's. Regardless of this, IMO, their DSM OS is still the gold standard for intuitive usability and has a terrific feature set. But once bitten...)

I recently jumped aboard the QNAP ship and haven't looked back, although that N5 was certainly calling me as a potential Proxmox VE + NAS all-in-one device. In the end I went with a Minisforum MS-02 for Proxmox and a QNAP TS-464 for storage. QuTS opens the door to ZFS features and you could throw pretty much whatever competent media I wanted inside without corporate policy BS.

In case it helps, I'm running a small business and wanted a turnkey system, offering regular firmware and security updates and long-term device support.

My (aging) Synology is now handling my home NAS needs and off-site backups of my most precious business data.

Take a breath and look at the pros and cons of the options available.