A power bank is easy cheap and fairly light alternative. Instead of carrying additional gaming device, I can carry a power bank instead...which is kinda useful even if I drain battery for whatever reason. If it completely dies, you'd be offline for like what 5 minutes until phone gets enough charge to boot again?

Yep, same here. I already have enough issues keeping my phone charged enough, playing games on it just makes it worse.

Every once in a while I do, but it's usually a really basic game that uses hardly any resources to run, like a simple board game app.

This, more than anything, killed Minecraft Earth if I recall correctly.

Even people who wanted to play during Covid couldn't because it would just eat the battery to death.