There are obsolete
full instructions here: https://hackaday.io/project/8678/instructions
The guide is 3+ years old. So many changes have been made to the Raspberry Pi's kernel and setup since then. Ever since the Zero W came out, projects like these haven't received much attention.
While the ESP8266 can connect to 802.11n networks, they're not very fast. Raw tests of packets generated inside the ESP8266 (so no SDIO or useful communications) max out at 7 mbps
(single thread) or just under twice that for multiple threads. Official throughput via the UART is 303 Kbps
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