Simple things and ROM hacking are not always going to dovetail together (
https://gbatemp.net/threads/the-various-audio-formats-of-the-ds.305167/ ), however for sounds then the vast majority of DS games use the SDAT audio format which has provisions for midi like sequenced audio, simple sound effects of wave type things and long form streamed wave audio.
If you only want to rip them for your own uses on a PC or something you do also have the option of using an emulator and loop back audio, a line in cable and more besides. Combine it with a light bit of hacking (mute background tracks or other noises as befits your whims, repoint things so if there is a secret theme that only a 20 hour sidequest can unlock and no test menu instead just plays it on the title screen or something) and can be even easier as there is a SDAT player using DS homebrew.
There are a variety of tools people will use.
Best of the bunch.
VGMtrans.
https://github.com/vgmtrans/vgmtrans
About as close as you might get to drag and drop.
VGMtoolbox
https://sourceforge.net/projects/vgmtoolbox/
Will need some hard to come by extras to make it work properly (some adapted part of a ROM) but this is what was probably used make all those nice 2sf files you can download to have clear playback on a suitably plugin laden version of winamp or foobar 2000.
ndssndext.
https://gbatemp.net/download/nds-sound-extractor.28818/
Will attempt to convert the SSEQ to midi, did better than the earlier sseq2midi but not as nice as the above. Most audio stings though will be swav at some level which is wave and easy enough.
Apparently there is a more modern rewrite/redo in
https://github.com/Oreo639/sdatxtract as well but never tried it.
crystaltile2 has some limited abilities here (click the little DS icon on the right hand side of the toolbar, find the sdat file in the new window, right click that and one of the options should bring up a new window again with things to look at and export/play.
vgmusic studio seems to be rising up the ranks.
https://github.com/Kermalis/VGMusicStudio
Probably a bunch of others I am missing but should be a start.