Suggestion for Android device for archival purposes?

I need an Android device for archival purposes, it has several requirements and I would appreciate any suggestions. I've done some research myself, but I would appreciate it maybe you know of something I haven't discovered.

Requirements:

• Must fit inside this Faraday pouch, or a different one that is of a similar price, and is both water and fire proof
• Must support an open OS (Degoogled, rooted Android ROM or Linux - both support touch interfaces, Kiwix, and storing and viewing files)
• at least 256GB internal storage to store the files
• at least 8GB RAM for running local AI models, preferably nearer 16GB
• Good battery life, since it will stay inside the pouch most of the time and I don't want to have to take it out to charge it every day
• As cheap as possible

I have no other requirements, it doesn't even have to have a camera, let alone a good one.

Thanks for all your help!