In Norway, your phone is your wallet, your ticket and your card. Here are the apps that will genuinely help, to install calmly before you leave. All are free.
Payment

Revolut
Multi-currency card, small payments without fees

Wise
Multi-currency card, alternative to Revolut
Car rental

Getaround
Peer-to-peer car rental
Parking

AutoPay
Parking by plate recognition

EasyPark
Parking (cities and some sites)

Bil i Oslo
Street parking in Oslo
Trains & transport

Vy
Train tickets

Ruter
Transport Oslo and Akershus

Skyss
Transport Bergen and Vestland

AtB
Transport Trondheim and Trøndelag

Reis (Reis Nordland)
Transport Bodø, Lofoten, north
EV charging

ABRP
EV charging trip planning

Uno-X
EV charging, charger map

Kople
EV charging (formerly Fortum Charge & Drive)

Elton
EV charging across operators
Outdoors & weather

YR
Weather, the most reliable

UT (DNT)
Hikes and trails
Customs & alcohol

KvoteAppen
Duty-free alcohol quota (customs)