If power is supplied through usb cable it should be possible to buy a sealed rechargeable gel battery to make the device truly portable. However in terms of bang for your buck I suspect that second hand notebooks or laptops are a cheaper alternative and come with built in battery and screen.
What inbuilt software does the Raspberry OS come with? Their website was not readily divulging it . . . Or is it a case like Apple where you have to buy each piece of software at monopolistic prices?

A basic computer for day-to-day tasks, coding, or media playback. It’s available starting today as a standalone machine for $70 or in a bundle including a mouse, power supply, microSD card, HDMI cable, and beginner’s guide for $100.