For the first time since the launch of tvOS and Apple TV4, you can try the upcoming version of tvOS without having a developer account. Apple has released a public beta of tvOS 11.
Try tvOS 11 beta today
Apple’s beta releases of iOS, macOS, tvOS, and watchOS have in the past been reserved for software developers. However, with the “public beta” program Apple started making the beta releases available to everyone.
This is the first time that tvOS has been included in the public beta. tvOS 11 beta 2 is available for download now.
The new features in tvOS 11 were not highlighted on stage at the annual WWDC conference but Tim Cook promised to talk ”a lot more about tvOS later this year”. New features include Airplay 2, HEVC decoding, auto-pairing of Airpods, auto-switching between dark/light themes, Home Screen Sync between multiple Apple TVs, new screensavers, notifications, Metal 2 game engine, and more.
Also read: tvOS 11: Airplay 2, HEVC, dark/light auto switch, screen sync, more.

If you want to try the beta of tvOS 11, Apple has posted a guide here. It is very simple to enroll and install the beta as it no longer requires you to connect the Apple TV box to a PC or Mac first.
Be aware that this is beta software so it may contain bugs. The finished version of tvOS 11 is expected to be released this fall.