And missing plenty of others too (e.g., WonderSwan, Neo Geo Pocket). And the site's graph even shows improvements during the DS era versus the decade earlier. And it also ignores the more hybrid nature of certain more recent consoles like the Switch versus handheld-only ones.
Wonderswan had fantastic battery life on a single battery. 20 hours or so if I remember correctly.
4 hours on TurboExpress may be pushing it. I think it's more like 3hrs+. There is no disappointment though as any kid should be amazed that getting that kind of graphics (one and only full current gen console -- none of the 2 older gens made it) into a 2 gameboy sized system for 3+ hrs is quite impressive.