Since I have spent the last 30-ish years in technology, the latter half as the director, for a smaller rural school district, I fear this message may get a bit too, umm, Nerdy? For that, I apologize up front.
While this post directly relates to the new Samsung 65" Smart TVs, I believe the basic concepts provided may be useful with other TVs without becoming a control-freak.
My solution: Convert "Smart Tvs" to Dumb Tvs used simply to display content which tends to follow the "Keep It Simple" philosophy.
@BrianEdwards --- I have given a lot of thought about the things you said and agree that having some R rated movie promo begin to play or one of the less than desirable channels auto playing in the background is not something we want in church. Or, having members watching/streaming shows they ought to be watching at home.
Since the smart tvs were installed in the relief society rooms in our stake, I have spent several days sitting in front of one of them (I'm retired now) searching for an answer that effectively and consistently blocks all that junk, good or not. Yet allows teachers the ability to present the content they want to use in class from the device/s they have and know how to use. However, since it seems Samsung knows best what we want and need, after agreeing to the Terms & Policies, all kinds of stuff downloads and installs, with the ability to download even more. Giving rise to tempting people to go to the meeting house to watch netflix, hulu, disney+, et al.
What I discovered was trying to manage all that stuff is like trying to hold 50 corks underwater all at the same time.
So, after many hours and tv resets, it seems the only way to prevent samsung from helping us is to never allow the tv itself to have access to the internet from the very start. Then when someone clicks Setup, it fails to reach their servers. (I REALLY do wish there was a way to get rid of the green banner with the setup button but my skill-set in hacking OS code just isn't there.)
In any case, for now anyway, I'm installing a cheap wifi router on the back of the tv (with really sticky velcro) to create a private network and uplinking the WAN port to Liahona network, wired. Then configure Parental Controls (I'm using a LInkSys E5350 although ASUS · NETGEAR · TP-Link · Google · eero · ARRIS · Motorola may well do the same thing. Your mileage may vary depending on your choice) to always block internet traffic from that tv's mac address. This isolates the tv from the internet but still allows user's Casting/Mirroring devices to reach the tv (has to be on the same network to work) AND still reach the internet through the church's firewall/filter.
Pushing pause here for a moment...
Two things make this method desirable for us, first it isolates the tv from the internet. WHY
does the tv even need it? Second, I have had so many complaints from members not being able to connect (display the Splash page actually) using their mobile devices to Liahona wifi, phones mostly. Using this private wifi eliminates that issue without compromising the church network.
On the tv, it is connected wirelessly to the private wifi obtaining its IP/DNS/Gateway addresses from it. Users are instructed to connect to the same wifi also obtaining the needed addresses AND putting both the tv and their device on the same network. Crucial for casting to work. "What about cheaters, you might ask." While It is true the tv could be rewired and allowed internet access by someone with enough tech savvy. Most will not bother. Even if they do, just Reset and reconfig the tv. And, if someone should try to connect the tv to the Liahona wireless, they have no way to click through and accept the terms on the splash so, no internet.
This private network business is only intended to be a short term work-around. I am hoping the network engineers will add another Group Policy in CNM to the current list in the building firewall which currently has, IoT and No Splash, It's a feature request that will always block internet access to specific devices, i.e. "Smart" Tvs so we don't have to build a private network to do the work. When that happens, the private network and wifi router goes away. You may wish to let them know you would also like the ability to block certain devices...hint hint.
And finally, since we all know in the church that if you want something done, involve the Relief Society....which I did. The Stake RS Pres. scheduled an initial 1hour training session in each building for leaders and teachers who would use the tv. There will be follow up sessions and some one-to -one sessions to be sure. For some, trying to take all the things even a "Dumb Tv" can do is like sipping from the fire hose.
If you have questions or wonder why this or that, I would be happy to address them here in the forum or privately: firstname.lastname@example.org
Thanks for listening.