The 6502 can't actually address more than that. The flash controller built into modern SD cards are also going to be significantly more powerful than the 6502. And I'm surprised you can even buy SD cards that small still!
Unless you use bank switching, which historically a lot of 6502 machines did use (e.g. Apple III/IIe/IIc, BBC Master 128, Commodore 128, Commodore CBM-II, etc)
What makes the CBM-II's 6509 fundamentally different from the C128's 8502+8722 combo? And what makes either fundamentally different from the segmentation scheme of the 8086/8088?
The C64 actually had 64K of ram, 4k of devices (graphics, sound etc) and 16K of ROM.