To be fair, this is not an Apple level device. 2.5 hr battery life is hilariously bad.
There are far more willing and paying customers on Apple products.
https://www.dotcominfoway.com/blog/apple-leads-android-with-...
Good mobile battery life with 'intense' graphics is an unsolved problem, Apple is not immune here.
I ended up buying one of those Anker laptop USB PD chargers, and they can recharge the Deck twice over, so I could actually spend nearly 8 hours fully utilizing the Deck's power without being tethered at all.
It's not like you do your 2 hour gaming sessions while moving around all the time. If you're sitting down, a thin wire to a decent size power bank isn't going to interrupt your gaming.