Nintendo Switch is 13 years younger than his elder sibling DS! Nintendo DS was launched in 2004, whereas the latest handheld console Switch was launched worldwide in 2017. Backward compatibility is still an issue in 2021 where gamers want to buy the next-gen consoles but the unavailability of previous-generation games for them becomes an obstacle!
The Switch’s external hardware is incompatible with the 3DS. Plus, it would cost Nintendo too much money to include backward compatibility with the 3DS. So sadly, the Switch can’t play 3DS games.
Even though the Switch comes with a full HD display and processor tons of times faster than the DS, Nintendo has not provided any backward compatibility in either of its handheld consoles across the globe.
Therefore, in my opinion, and research, it is not possible for Switch to play the DS titles on its hardware until or unless the company itself codes backward compatibility in its handheld gaming consoles.