I think you might be mixing up a few things here. As we say, you’re comparing apples to pears 😊. This is mostly a matter of form factor. Technically, you can build a NAS out of a laptop, but it’s far from ideal—especially since you’d likely end up using external hard drives via USB.
HexOS and TrueNAS require drives to report their individual serial numbers, but many cheap USB enclosures skip that and just report a generic serial for all connected drives. That causes issues with drive detection and undermines data integrity.
In your case, the hardware is also quite old and doesn’t meet the minimum requirements.
That said, this doesn’t mean HexOS isn’t suitable. On the contrary, it’s very easy to use—just keep in mind it’s still in beta. But if you’re considering buying something like a UGREEN NAS, there are other NAS form factor devices that might be more interesting. For example:
https://aoostar.com/collections/nas-series
https://www.kickstarter.com/projects/lincplus/redefining-nas-style-power-and-usability-with-lincplus
These devices let you choose your own OS, whether it’s HexOS, TrueNAS, or Unraid.
Another option is buying a NAS from UGREEN, QNAP, ASUSTOR, or TerraMaster (but not Synology). You can use the default OS or install something custom like HexOS or TrueNAS, if the hardware is supported.
See: https://www.youtube.com/watch?v=xmFb_kO5V3Q So, in short: there are lots of options.
Could you tell us what you plan to use the NAS for? That might help us give you more targeted suggestions.