You can write your Python code in any IDE you like. Boards that have native USB such as the SAMD boards (Arduino Zero, MKRZERO, Adafruit M0, etc.) will show up as a flash drive on your computer once you have installed the CircuitPython or MicroPython firmware so you can just save the Python code to the flash drive. That should work seamlessly with any Python IDE or text editor.
The ESP8266 doesn't have native USB so uploading your code to that board is done through either a virtual COM port or over WiFi. That will require either a plugin for standard Python IDEs or a specialized IDE, both of which are available.
So yes, it is possible, whether you want to use an official Arduino board or a competitor. You just need to use a microcontroller that is supported by MicroPython (ESP8266, STM32F4, ESP32, probably some others) or CircuitPython (SAMD21, ESP8266). It really doesn't matter who makes the board as long as it has the right microcontroller. You can buy some with the MicroPython or CircuitPython firmware pre-installed and the ones sold in cooperation with the MicroPython or CircuitPython developers do support further development work but it's easy enough to flash any board with the firmware.