The Retro Wifi SI is an ESP8266 and MAX3232 based wifi modem prebuilt kit including a 3d printed casing. When plugged into an old computer such as an Amstrad CPC (via Pace RS232) shows as a generic Hayes compatible modem. It allows the user to connect their Amstrad to WiFi and get on the internet such as using BBSes (Bulletin Board Systems) or telnet into other machines on the Local Network.
Availability and more information can be found here: https://www.simulant.uk/shop/retro-vintage-computer-wifi-modem-rs232-serial-hayes-compatible