The Arduino Create for Raspberry Pi builds Linux executables which are downloaded to Raspberry Pis running Raspbian Linux. It might work for other versions of Linux but I think only Raspbian is supported. Create also supports BeagleBone and Intel CPUs running Linux.
The "sketch" runs as root but is otherwise a regular Linux program. I do not see any option for a bare metal/no OS mode. It is possible to run more than one sketch at the same time.
As an alternative, it is pretty easy to build code to access the Pi GPIO, I2C, and SPI using the wiringPi library and gcc/g++. No need for a Cloud server to generate code when the Pi can run gcc/g++. In addition, there are wrappers for Python, Perl, Ruby, Java, nodejs, etc.