I understand your perspective, but it seems to me that Android TV creates the appearance of an open garden by painting the sky on the walls and ceiling. But in reality it is a labyrinth meant to keep you trapped that they allow other companies to setup small garden plots in.

What happens when I want to install an app exclusively available on F-Droid? Or what if I own an Amazon Fire tablet with apps purchased from the Amazon app store? These apps can't be accessed through the Google Play Store.

While the apps you install from the Google Play Store act as content aggregators, it doesn't mean you aren't confined to the offerings of the default app store. Depending on your Android TV device, you might encounter hurdles or find it impossible to use alternative app stores.

Epic v Google was about Fortnight and the 30% fees on in-app purchases which had to go through Google with no way around it.

They key term there being "with no way around it". Epic's concern was precisely this lack of alternative app store availability. In Epic's own words from their verdict announcement:

"Throughout the trial, we saw evidence that Google was willing to invest billions of dollars to hinder alternative app stores by incentivizing developers to abandon their own distribution plans and exclusive agreements with device manufacturers that excluded competing app stores. ... Google imposes a 30% fee on developers because they have effectively prevented viable competitors from emerging."

Epic not only aimed to reduce the 30% fee but also sought to prevent Google from imposing artificial barriers that prevented users from accessing alternative app stores on Android devices. This was done with the intention of launching an "Epic Games App Store" as an alternative, bypassing the 30% all together.

To relate this to the garden metaphor. You are so focused on the garden fiefdoms Google gives you access to, you never notice you are being prevented from leaving their Garden Kingdom. (Or to put it another way, the Google Play Store is a mall that hides the exits and pays other stores to prevent anyone from talking about other malls)

Fortnite serves as a prime example of this issue. While a capable Android TV device can run Fortnite, you can't download it from Google Play, necessitating sideloading. Many Android TV devices even restrict you from downloading browsers or installing APKs from sources outside the Google Play Store. This means you'd need to research how to sideload it, even though it's technically possible.

In contrast, consider the Steam Deck, where there's only one gate: the "Switch to Desktop Mode" button. Once you cross that threshold, you have complete freedom, with only developers' willingness to support it standing between you and any software you desire. If Epic were to develop a Linux version of the Epic Games Store, it would run on the Steam Deck, and they could even use Proton, an open-source software, for compatibility. You could even add games from it, or the launcher itself, to your list of Steam apps and launch it from "Game Mode". So you could switch between launchers at will (I have done this with Battle.Net, Lutris, and the Heroic launcher without issues or blockers).

From this point of view, the SteamDeck is a fully open garden with a single very visible gate leading to a fully open world (albeit sometimes an untamed wilderness). And as was said earlier, if you find an interesting "plant" out there, you are free to bring it back to your garden, no questions asked. When you see a wall outside that garden, it's not because you have been walled in, but rather walled out, or at the very least deemed unworthy of entry.

I can understand preferring to live in Google's Kingdom, where all the conveniences you are used to are readily accessible. And I can see how the SteamDeck's single well kept garden in an untamed wilderness where you have to learn how to get to any other garden would be less desirable. After all, a home is made up of walls, and even if you are trapped inside, you are "free" from the inconveniences of the wildernesses, but don't mistake the wilderness for walls.

Edit/P.S. To be fair, Android TV's often try to bar your path, but it's not nearly as bad as iOS devices. Most of the time, you can leave the "Google Kingdom", it just requires as much (or more) research and time investment than doing so on the SteamDeck. And unlike Valve, Google makes back room deals to keep it's garden a labyrinth and prevent open discussion of other gardens, so users never even notice they can't leave.