While I don’t agree with you on the usability of Big Picture on Windows, I certainly agree with you on one point; it would be great if other game launchers could be seamlessly installed on the Steam Deck.
However I’m happy that other launchers are available for those who go through the slightly lengthy process.
PS: I don’t agree there are 1000s of games not able to run on the Steam Deck, it’s mostly these games on the list. (areweanticheatyet.com)
what I want is an official way to install and launch third party games, or at least third party launchers from within Steam
While I think this would be great for everybody, but I think the money-oriented guys inside Valve would think it’s a bad idea. If you present an easy way to install other launcher to the masses, people will be swayed away from buying from the Steam store. Valve wants publishers to stay on their store; that is their trump card. I remember someone tried putting an alternate store on Steam Store and it was quickly removed to avoid legal troubles.
Windows absolutely does have a Big Picture mode. You can set up Steam to launch on boot straight into Big Picture. If all you want is to play Steam games you never have to use the Desktop on Windows either
BigPicture in Windows is extremely nerfed compared to Bazzite/SteamOS which I have detailed in this comment and further elaborated in this post. The tl;dr version is “yes you can use BigPicture but you still have to deal with a lot of Windows shenanigans”
Source: I’m a user of both Steam Deck OLED and ROG Ally.___
The current way to play Epic/GoG/Amazon games on the Steam Deck is
Switch to desktop mode
From the app store, search for Heroic Launcher and install
Launch Heroic
Put login credentials for Epic/GoG/Amazon
Wait for your library to get populated
Install the games
Add Heroic as a non-Steam application
Switch back to Big Picture mode
Launch Heroic
Play games
While the number of steps seems like a lot, if you compare against the Windows equivalent, it’s not a lot simply because Windows has no Big Picture/console mode. I personally hate the desktop mode in Windows because I’m forced to use the touchscreen constantly.
What would you like to be changed in this process?