When building vyos-1x package you will get a XML cache definition of all CLI commands.
After build you can check: ./python/build/lib/vyos/xml_ref/pkg_cache/vyos_1x_cache.py or on a running system, vyos.xml_ref package with helper functions.
Some good starters would be:
from vyos.xml_ref import cli_defined
from vyos.xml_ref import default_value
That might give you some live Python code to generate a list of all available commands. Internally we have found a similar issue - see ⚓ T7590 cli: define a helper that generates a list of ALL available op-mode commands to embed in smoketesting maybe both can be handled together.