The phrase "a single device or" is correct and usable in written English.
It can be used when discussing options or alternatives, particularly in a context where you are comparing or listing devices or items.
Example: "You can choose to connect a single device or multiple devices to the network, depending on your needs."
Alternatives: "one device or" or "a lone device or".
They all take the same approach: you can buy a single device or a three-pack to set up a mesh.
The financial fallout is expected to be unusually large and complex because the episode involves a class of products, not a single device or just one company.
The commands can be sent to a single device or a group of them.
A RFC is a single device or system capable of functioning either as an electrolyzer or a fuel cell.
That felt a bit backwards: If response had been so strong, why give away a single device or discount?
Imagine a high resolution Scrabble, Chess, Checkers, etc. game on the tablet device where you can play either simultaneous multiplayer on a single device or across multiple devices.
Multiple layers of quadrupole ion traps, with 121 trapping units in each layer, can operate as a single device for MS or MS/MS analysis, or as a series of mass-selective trapping devices with interlayer ion transfers facilitated by AC and DC voltages.
A single device integrating two or more monocular cameras with small baseline (i.e., the distance between focal center of the cameras).
Can you think of a single device, display, web page, or anything that has a 960×540 resolution?
The integration of selective catalytic reduction (SCR) and diesel particulate filter (DPF) into a single device (so called SCRF® or SDPF) can decrease the packaging volume and costs in modern diesel exhaust aftertreatment systems.
As we'll see, the smartphone's role will change from that of a single device to a hub, or nervous system, controlling a wide range of peripheral products.
