Commercial non-alcoholic beer is made by boiling it under vacuum such that the alcohol boils off at ~30C. This is less detrimental to the beer's flavor.
In Germany we have something called Malzbier (Maltbeer) and it basically is lightly hopped, yet unfermented sweet wort with carbonation. When I was a Kid I loved this stuff. And when my Kids are older I plan to brew this with them.
But I haven't done much research on this yet. The only information I have are some threads on a German homebrewing board.
There are 2 ways of approaching the problem of getting the carbonation into the beer:
the stopped fermentation method:
Here the wort is actually pitched with yeast and immediately filled into bottles that are capped. There it will produce CO2 and carbonate it. Once enough CO2 has been produced, the yeast needs to be killed by pasteurizing the bottles in ~70C water. Once this is done the Bottles can be cooled and stored. There will be about 1% alcohol in the bottles.
the force carbonation method:
The wort is placed in a keg and force carbonated. This seems to be the easier of the 2 methods and the resulting beer doesn't contain any alcohol.
But before I make this I will have to do more research. Especially regarding the shelf life and potential contaminants since there is less hops, less alcohol and lots of fermentable sugar in there. It is important to find out if there is any danger of pathogens being able to thrive in there.
BTW: I was able to find this Malzbier in the supermarket once. The only brand I know is Vitamalz. And there is always root beer, which I can't stand.