Google Nest Hub
The Google Nest Hub serves a mixed purpose for me. Sometimes, I use it as a second screen for playing Netflix / Twitch / YouTube. Sometimes I run music on it if I'm playing on my Xbox. Sometimes, if I'm feeling extra risqué, I'll even use it as an actual smart home device to control lights!
At £89.99, it is the perfect secondary screen for how I use it. It's content that I'm primarily listening to, whilst getting actual work done on my 21:9 display. If it's something I plan on actually watching witout also being distracted, I'll watch on my screen.