Steam now allows you to copy games to Steam Deck and other PCs over a local network

engadget.com:

Valve is giving Steam Deck users with slow internet connections or bandwidth caps a new way to install games on their devices. The latest Steam and Steam Deck betas add local network game transfers, a feature that allows you to copy existing files from one PC to another over a local area network. Valve says the tool can reduce internet traffic and lessen the time it takes to install games and updates since you can use it to bypass the need to connect to a Steam content server over the internet.

Hello! We've just shipped a Beta update to Steam and Steam Deck that includes a new feature: Local Network Game Transfers.This allows Steam users to install games directly from one PC to another over a local network, without having to download and install from the internet. pic.twitter.com/bv9xThZCoS

“Local Network Game Transfers are great for Steam Deck owners, multi-user Steam households, dorms, LAN parties, etc,” the company points out. “No more worries about bandwidth or data caps when all the files you need are already nearby.” Once you’ve installed the new software on your devices, Steam will first check if it can transfer a game installation or set of update files over your local network before contacting a public Steam content server. If at any point one of the devices involved in the transfer is disconnected from your local network, Steam will fall back to downloading any necessary files from the internet.

By default, the feature is set to only work between devices logged into the same Steam account, but you can also transfer files between friends on the same local area network. It’s also possible to transfer to any user on the same network, which is something you would do during a LAN tournament. Valve has published a FAQ