After getting some suggestions here already, I'm considering a pair of 1s or 3s (rather than a single 5) for our 25 m2 / 270 f2 living room. I might add a sub at some point, but I thought I'd try without first. It seems clear that going for two speakers is better than going for a single speaker.
But now what do I do with my TV? It's currently connected to an old stereo system that I was hoping to get rid of when we upgrade our audio system now. Play:1 and Play:3 don't have line in, so I can't use these with the TV. Only Play:5 and CONNECT have line in, and I'm not planning to get any of these for the living room. So do I have to buy a pair of 5s for the living room if I want two speakers? I'm assuming it's not a great option to couple a 5 with a 3 or a 1 for stereo sound.
Edit: a Playbar would obviously be a solution, but I wasn't planning to get one of those either... Though a playbar and two 1s would probably be cheaper than two 5s, which seems to be the alternative.