The datasheet makes the ESP-01 look limited (only 2 usable I/O pins, needs level shifting, awkward boot sequence). And honestly, for a new project, you should probably buy an ESP32-C3 or an ESP8266 D1 Mini.
: UART pins for serial communication. These default to a baud rate of 115200 for AT command firmware, as noted by Tech Explorations . esp-01 datasheet