While the Raspberry Pi has very good support for an I2C bus, a lot of very cool chips – including the in system programmer for just about every ATtiny and ATmega microcontroller – use an SPI bus.
If you want to program in Python see Raspberry Pi IoT In Python Using Linux Drivers. There are many specific device drivers which make use of the I2C bus and, as in the case of the SPI bus, there is ...