As it happens, there is a former Rim Worlds Republic world called
Gabenstad, which fell off the Inner Sphere and near Periphery maps at some point after the end of the Second Succession War. In the "contemporary" IlClan Era setting, the world is, or would be, in unclaimed space close to the Rim Territories.
So, if a Goliath Scorpion Seeker was to uncover a cache of LosTech devices from this lost world, and then find a way of making them functional once again, might this be the result?
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Beyond gaming mode, SteamOS has a desktop mode which enables the Steam Deck - LCD or OLED - to be used as a desktop Linux PC.
Although, it would be advised to do this while using a few added peripherals:
Said peripherals are also recommended for playing games designed to be played on a larger screen with a keyboard and mouse. Although, using the OLED screen while docked is not an altogether bad alternative.
SteamOS has Mozilla Firefox installed as standard, though other apps - such as Google Chrome, LibreOffice, and so forth - can be installed from the Discover Software Centre (an "app store" for Flatpaks).
Note, however, that SteamOS sets the system memory to read-only by default. While it
is possible to alter this, Valve only suggest that option for someone who knows what they are doing - not least since any edits made are liable to be wiped in the next OS update.
So there are two main ways to get new things running on the Steam Deck: to download (or transfer) and install them in the Steam client itself, or to use Flatpaks from the Discover Software Centre.
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And to follow on from what is noted above, HBS'
BattleTech is now listed as "Playable" on Steam.