How to get test cases list in Robot Framework without launching the actual tests?

You can check out testdoc tool. Like explained in the doc, "The created documentation is in HTML format and it includes name, documentation and other metadata of each test suite and test case".

Robot test suites are easy to parse with the robot parser:

from robot.parsing.model import TestData
suite = TestData(parent=None, source=path_to_test_suite)
for testcase in suite.testcase_table:
    print(testcase.name)