Yes, spending the required time in HK, Macao or Taiwan would reset the clock, but of course this assumes status quo on these regions remains until 2024. Also not knowing the specifics of tax residency in said territories themselves.

But is it really 31 days? I seem to recall it was 3 months, which for me is a bit long for a single holiday trip even every 6 years. 1 month sounds too easy for most expats. But maybe I remember wrong or confuse with older regulation.

Under the old Five-Year Rule, you could reset the clock with 90 cumulative days outside China in any given year. But that was left out with the Six-Year Rule, and the only reset now is 31 consecutive days.

90 cumulative days was actually advantageous for expats who lived in Hong Kong but commuted for work to the mainland.

Reading all of the above it appears that foreign income that is only derived from pensions would not be taxed.

"The IIT levy is applicable to people earning wages, salaries, pay for authors or personal services, plus income from royalties, business operations, interest, dividends and bonuses. Revenue from property leasing or transactions, as well as contingent income, is also taxed."

Did I read it correctly or just make a hopeful assumption?

The second source I listed above includes the category of "Contingent and other forms of income" which are taxed at 20%. I don't know if "other" casts a net over pensions. If they are exempt, many retirees will still be on the hook for interest and dividends.