You are right in regards to the current movement. In the 5 demands it says, "...implementation of universal suffrage for Legislative Council and Chief Executive elections"

Which could feasibly be done within the confines of the basic law. It is true many pro-democratic HKers don't want independence.

For some more context for those reading into it: https://en.wikipedia.org/wiki/Hong_Kong_independence vs https://en.wikipedia.org/wiki/2019_Hong_Kong_protests

But I should also be complete and let you know there is a fledgling and growing movement, the so-called "Republic of Cantonia", who believe all Guangdong should be break into its own nation. You can see the flag here: https://commons.wikimedia.org/wiki/Flags_of_active_autonomis...