Roku Premiere+ (3921X)

Overview
The only difference between this Roku Premiere+ (3921X) and the Roku Premiere (3920X) is the remote included with the device.

The Premier+ (3921X) includes the Voice remote with TV power and volume buttons while the Premier (3920X) includes the simple remote.

The wireless chip ID is not legible in the FCC photos but it is a 24-pin QFN from Realtek.

This suggests a RTL8188FTV (USB 2.0) or a RTL8189FTV (SDIO). Both are 1x1:1.