Nowadays, a smartphone is an all in one device that can replace many devices such as a:
laptop – using apps on phone that are installed on your laptop
desktop / PC using apps on a phone, especially the most common ones such as Office Suite: Word, Excel, PPT, Outlook
scanner – very convenient to use your phone when you do not have a scanner or a multifunctional printer within reach, or it is being used by someone else, or it is out of order, or simply use it because it is easier and faster
video camera – latest phones can make even 8K UHD videos – very high quality
snoring, heart rate, oxygen level, blood pressure and many more devices for health and wellness monitoring
GPS tracker – no need of updating the roads from the old GPS, use the offline and online maps for travelling
calculator, flashlight,compass, timer, meter, and many more measurements or everyday use tools