I'm aware of how roundabouts work thanks.
Cars don't stop in roundabouts. They're made for cars. Drivers don't pay enough attention to pedestrians when in motion. They never have.
Traffic lights stop the 2 ton killing machines. Roundabouts do not.
Roundabouts are strictly worse. Traffic lights are better because they inconvenience drivers more and there's nothing more important than inconveniencing drivers.
Matter is absolutely game changing: it's gotten full support from Apple, Google, Amazon as well as most HA manufacturers.
With Matter you'll see significant improvements to whatever system you use to control your HA because you don't need 7 protocols and 3 hubs and 4 apps to run everything: it's the open standard we've needed with 1 protocol, 1 setup and pick your preferred app.