How can I download steam games files on android?

I am trying to download the files from a windows game from steam on my android phone.

I don't want to remotely start a download on my PC but download the game directly to my phone. At home I have limited 300gb of bandwidth, but my friend has unlimited internet, I can't take my PC to his house but I can take my phone and download the files on it, and later transfer them to my PC.

It need to download them only using the phone, not a PC, so I don't need to use my phone as a portable storage. I need it as a download machine. I.e. I want download game files to my phone via my friend's unlimited internet connection, then I want to transfer them to my PC at home where I'm going to use them instead of actually downloading game via my limited connection.

Is there any way of doing this? I am even open to writing my own app if there is an API open to use for android.

This should be possible in the future using Wine, but I just spent an hour or so trying using Wine 3.14 for Android and could not get steamcmd.exe to run.

I did not try the real Steam client, though I highly doubt it would be usable if it even did run unless you have a tablet or are willing to use Steam's terminal commands to attempt to get it to work well enough to install the game =\

It may currently be possible using Limbo, a QEMU-like app for Android, but I really didn't even know this existed until a few minutes ago. It's also going to take me a long while to try to get anything to happen there -- I truly hate installing Linux, my phone isn't rooted so it may not work as easily as a rooted device (though Termux + NodeJS are doing amazing), and I probably don't have enough space for an OS install with updates + steamcmd + even a small game on here either with currently less than 4GB of space (but I will try to make space).

I know Linux installs without a GUI can be very small, but I like to have some free space and they do take a bit. And just for fun: Wine on Android is only about 130MB when installed from it's 123MB download (as of 3.14).

Edit: Limbo sucked. UserLAnd seems promising as you have root by default, but after literally hours of trying I just gave up. multiverse, multiarch, running as root, installing & running from root. No matter which sets of directions I follow it continues to fail, possibly because it's Ubuntu 18 & everything is for around 16 or lower. GNURoot Debian may also work just because it's got root.

It is not possible to download Steam games directly to your phone. Your phone can only act as a storage device (not as a downloader like you described), just like a USB stick or an external hard drive.

Your only option if you want to download the game from your friend's house is to use his computer and transfer the files manually to your phone, but it would be a better idea to use a USB stick or an external hard drive.

A workaround to your download cap in your home's network, is to start the download at the end of you billable month to take the remaining data left in your data cap, and finish the download at a later date.