What do you mean? An amplifier that can drive speakers that's also a streaming device? That exists at various price points. Anywhere from a raspberry pi taped to a "dumb" amplifier all the way to various Roon streamers. Although at both super-low and higher price points, things tend toward individual components for flexibility and diy reasons. But that's easy enough to work with to get something that both looks and sounds good.
Sonos's one plays nice w/ Sonos's ecosystem, but if you don't need that there are other solutions.
I mean an amp with only: HDMI eArc in, 5 speakers out, sub out, power button. And <$500. I don't actually want or need the Sonos ecosystem. I also don't want or need a huge, visually intrusive box with dozens of knobs and seemingly hundreds of rear connectors - as is the case with the AVRs. I guess it's too niche for Apple to make one.
Sonos's one plays nice w/ Sonos's ecosystem, but if you don't need that there are other solutions.