No 3DS game has used an 8 GB card, and few have been 4 GB. It's relatively expensive. That's why 32 GB is probably the limit for the NX's gen anyways.
There's more 4GB 3DS games that people are generally aware of. I also doubt they're really that expensive anymore given how niche some of the titles are.
Bravely Default
Bravely Second: End Layer
Donkey Kong Country Returns 3D
Dragon Quest VIII: Journey of the Cursed King
E.X.Troopers
Hatsune Miku Project Mirai 2
Hatsune Miku Project Mirai DX
Hyrule Warriors Legends
Inazuma Eleven Go - Light / Shadow
Inazuma Eleven Go 2: Chrono Stones - Thunderflash / Wildfire
Inazuma Eleven Go Galaxy - Big Bang / Supernova
Metal Gear Solid: Snake Eater 3D
Monster Hunter 4 Ultimate
PachiPara 3D: Deluxe Umi Monogatari
PachiPara 3D: Ooumi Monogatari 2
PachiPara 3D: Ooumi Monogatari 2 with Agnes Lum
PachiPara 3D: Premium Umi Monogatari
Resident Evil Revelations
Samurai Warriors Chronicles 3
Senran Kagura 2: Deep Crimson
Shin Megami Tensei Devil Survivor 2: Record Breaker
Xenoblade Chronicles 3D
Yo-Kai Watch 3 - Sushi / Tempura
As for NX topping out as 32GB, no cart/card based Nintendo platform in history has launched with it max rom size available day one. I doubt NX will break that trend.