That's handy if you want to run old qbasic code, since typically that code expects to be able to poke hardware registers to do anything beyond what the built in bits of basic can do (for example, adding mouse support or playing sounds beyond beeps).
Haven't tested, but QB1.1 or 4.5 should also work with vDosPlus [1]. The original vDos apparently has issues with keyboard input in QB, but, arguably [2], this has been fixed in vDosPlus.
There's also that bootable USB stick with FreeDOS or SvarDOS or smth on bare metal + native QBasic within it. I imagine this would actually make a really nice, responsive and distraction free environment for a child. DOS could also boot straight into QBasic via autoexec.bat, or present some fancy personalized menu.bat for the child, which is, yknow, cool. Or... it sure used to be in 1995. :)
As a non-native English speaker, I must also say that QBasic's simple syntax is incredibly good for teaching programming to children. Not too many footguns with weird (#$ymb0ls{}) either. It really is a great teaching language, even in 2023.
2: List of additional features as compared to original vDos: "Keyboard IRQ1/INT9 handling for running programs such as MS-DOS EDIT, QBASIC, Visual Basic and XyWrite": http://individual.utoronto.ca/wengier/vDosPlus/featurelist.h...
Unfortunately, Magic Dosbox for Android doesn't seem to work very well with QB45.exe...
Aside from linking with assembler, what QuickBASIC 4.5 funcs give you the ability to interface with the hardware directly in the fashion you're describing?
With those two you could do anything.
Writing a full-on IBM PC/DOS emulator is beyond the scope of this project -- the project's goal is my dad's request to "show off programming while drinking coffee" :P.