I had a Buffalo LinkStation NAS for almost a decade. It replaced a Time Capsule and, at the time, the LinkStation was one of the few NAS enclosures that could act as a Time Machine backup. It served me well but was recently retired for a QNAP NAS.
These days, you'll probably have difficulty finding a NAS enclosure that doesn't support Time Machine. There's a couple of additional but easy hoops to jump through to set up TM on a non-Apple backup device but, once it's done, the operation is seamless.
FYI, I believe you will have to partition the backup drive in order to have non-TM content on the drive as TM cannot coexist with other file types. You will need to factor this into your purchase decision (i.e. how much capacity you need on your NAS).
However, rather than messing with partitions, what I have done is add an external drive to my Mac on which I store all my media, and I back it all up - including the external drive - to my QNAP NAS. The external drive is an SSD for speed and quietness, while the NAS is loaded with beefy HDDs for cheap capacity as response time and noise is not an issue.