Phone charging is one of the lowest-power tasks in an emergency kit — you don't need a large power station just to keep a phone alive, though a slightly bigger unit buys useful flexibility for other small devices too.
BLUETTI Elite 10 Mini: pocket-sized, phone-focused
At 128Wh, this can recharge a typical phone roughly 20+ times on a single charge — genuinely more than enough for extended emergency phone use, in a package small enough to keep in a go-bag without a second thought.
EcoFlow RIVER 3: phone charging plus a little more
The extra capacity over the Elite 10 Mini means it can also handle a small radio, a headlamp charger, or a tablet alongside phone charging — useful if "emergency phone charging" needs to stretch to cover a couple of household devices.
Don't forget a car charger as a free backup
A standard USB car charger and cable, kept in the vehicle, is a free, always-available backup for phone charging specifically — worth having even if you also own a dedicated power bank, since it doesn't compete for the same stored charge.