No, the o/O is optional (hence in square brackets), only the leading zero is required. All of these are valid octal literals in Go:
0600 (zero six zero zero)
0_600 (zero underscore six zero zero)
0o600 (zero lower-case-letter-o six zero zero)
0O600 (zero upper-case-letter-o six zero zero)
The distinction between code, config and data is being erased. Everything is a soup now. Data is application, configuration is code. Code is an intermediate, volatile thing that is generated on the fly and executed in the temporary lambda containers.