The problem I have with DS/3DS format is that they're super uncomfortable to hold for me, so I wouldn't even consider buying one.
When it comes to handheld emulation in general, Steam Deck is versatile and affordable. The DS emulation in particular works great with two monitors setup. It's not out of the box solution, and it's finicky to configure, but when it works, it's an ultimate DS/3DS experience IMO. Example: https://steamdeckhq.com/tips-and-guides/how-to-play-3ds-games-dual-screen-with-citra-and-steam-deck/







