Just search for some dvd ripping software that can demux the different streams according to the chapters' cuts. Back in the days I used DVD Decrypter
DVDDecrypter - IFO Mode
Tools - Settings - IFO Mode - File splitting BY CHAPTER
disclaimer: I haven't done anything with dvds in forever, that's the workflow I just found randomly searching to make sure dvd decrypter divides by chapter as I recall..
since the technology behind DVDs is quite "ancient" I guess even old software like that can do the trick. You'll have to encode the audio to your listening format of choice, but that's an easy task.