This leads to an interesting philosophical debate about where the line to "cheating" is. I'd imagine the NES is more than capable of handling HTTP. I own a small managed network switch with a Web UI (and CGI) all running on an 8051 built into the switch ASIC, and if that can do it, it doesn't seem like such a far fetch that the NES can. The hard part is storage and I/O.
This is purely theoretical, but a 6522 could be used to bitbang SPI, opening the possibility of adding an SD card and Ethernet controller (with a chip like the Wiznet W5500). Add a small amount of SRAM (~16/32Kbit) and a loader ROM, and you'd be able to make the NES into a workable general purpose computer using only the cartridge slot. If needed, one could steal an interrupt from the expansion slot.
Admittedly, this could still be considered "cheating" because the W5500 has a built-in TCP/IP stack, but personally I would feel comfortable saying the NES is hosting the site.
I feel like this would definitely be possible. I was reminded of https://mitxela.com/projects/kiloboot, which uses an ENC28J60 for the ethernet stuff. I feel like you could probably quite easily bitbang SPI, given it's quite a forgiving protocol, just dedicate a couple of addresses in the memory space to interact directly with the bus (maybe with a separate shift register chip if you want to make things a bit easier). If you give up writing anything to the screen, I'd imagine you could just spin until something happened on the ethernet side, then read the requested path, pull some data off the ROM that corresponds to that path and send it back again
This is purely theoretical, but a 6522 could be used to bitbang SPI, opening the possibility of adding an SD card and Ethernet controller (with a chip like the Wiznet W5500). Add a small amount of SRAM (~16/32Kbit) and a loader ROM, and you'd be able to make the NES into a workable general purpose computer using only the cartridge slot. If needed, one could steal an interrupt from the expansion slot.
Admittedly, this could still be considered "cheating" because the W5500 has a built-in TCP/IP stack, but personally I would feel comfortable saying the NES is hosting the site.
Bitbanging SPI with the 6522 -- https://wilsonminesco.com/6502primer/potpourri.html#BITBANG_...