Ohh such a good question! haha I was wondering whether I could download Arch ISO with the normal Android I theoretically brought with me and flesh a MicroSD using the smartphone itself.

Well, regarding to download I could use Transmission or any torrent client for Android. For checking the sha256 hash I just did a quick test here and it's possible with Termux:
 https://image.nostr.build/0336c498e4c5babb0627ac82e555d6cb517ee22def6c8afee1b84ad32c573984.jpg 

The only open question now is whether I can flesh a MicroSD using Android, I will take a look at this specific topic and bring the answer later haha