You can find 3ds Roms using this link here https://theromdepot.com/
Told safe by this Reddit post here https://www.reddit.com/r/Roms/comments/9gzto2/safe_rom_sites/
"Everyone is flawed one way or another, even the best of us, so why bother being Insecure "
In my opinion this site would be much better if it had Nintendo 3DS ROMs (not that it isn't good already). Although it would be A LOT of hard work, I think it would be worth it. To already save some work, the main emulator usede for 3DS games is Citra. If you could or wished to do so, you could ask for help within the community for ROMs.
Of course this is an idea, not a demand. You do it if you wish.