It might be an interesting idea given that the Steam Deck has reasonable amount of RAM/GPU. The main issue for a knowledge base might be the lack of a physical keyboard though.
Missing a chance to note (or configure for?) installation on a Raspberry Pi --- that'd make an affordable option to leave powered down, but ready to go in an EMI-shield/Faraday Cage.
https://internet-in-a-box.org/
https://wrolpi.org/
I used it on a long train trip. There was no internet due to drone attacks, and with Kiwix I could browse pre-downloaded Wikis