“For a lot of companies, the absence of webview support on tvOS is going to be painful.”
Not as much “Painful” as a deal-breaker.
The last figure I saw from last year was 8000 apps in the TVOS app store (I lay claim to being the developer of one of those apps in the store), which is disastrous for a platform aimed at a wider public.
Hardware-wise, the base device is well powered but hamstrung by the remote control which was poorly designed (there’s a very good reason why remotes have replaceable batteries), with a slim design pretty much guaranteed to be lost in the rough and tumble of a regular family environment. This is a device that seems to have been targeted for review writers on tech websites and single-dwelling Apple fanboys. Entering a username or password is a nightmare.