Should I build a NAS/DAS/Home Server?

[The Great Milenko]

Sounds like you want a raspberry pi plex server
Plex should be able to run on your smart tv's, tablets and pc's so it's boomer proof.
ras pi's are basically just mobile phones with a linux desktop os so they sip power, you could use an older laptop to but it might not have usb.3 and other modern features.
View attachment 3835797
pi + hard drive

Would this be good enough to eliminate cloud storage for files? Pictures, etc. No video needed.

 

[Car Won't Crank]

Yes do it. Consider a last gen AMD Ryzen cpu. You can add ECC memory later if you need. Good starting point and room to do more like docker stuff or add fancy NICs.