See Marty Setup, Calibration and Troubleshooting Guide for WiFi setup walkthrough & troubleshooting.
The endpoints available in “hotspot mode” are as follows:
/scanreturns a JSON-encoded list of the available networks
wifisave?s=Network&p=Password&name=Namesaves the network config (Network, Password) and the new name (Name) on the ESP.
Managed, Unmanaged, and Websocket connections are all available when operating in hotspot mode. JS-based and UDP-based service discovery are not available.