To build on Pedro's discovery of support for unnamed sections in Python 3.13, an example:

import configparser

config = "config.ini"

cparser = configparser.ConfigParser(allow_unnamed_section=True)
cparser.read(config)

value = cparser.get(configparser.UNNAMED_SECTION, 'key1')

and while OP has no need to write/modify the original file, for those who do:

cparser.set(configparser.UNNAMED_SECTION, 'key1', 'new_val')

with open(config, 'w') as cf:
    cparser.write(cf)