Genuinely interested and not a goady question but is there a point in history where the line is drawn on colonizers who have to apologise for past activity?
Is there are point of (western?) enlightenment where we knew 'collectively' that invading and taking a land from an existing settled people was wrong?
The UK was colonized by the Roman Empire - but is that just too far back in history to care about? Then the Celts, then the Anglo Saxons.
Spain - also a major colonizer in current modern history - was colonized by the Romans and the Greeks and was also a colony of England and France at one point.
Also - Australia is not a colony now - they still have Charles as a figurehead head of state but that's easily changed when they want.
Better to concentrate on the countries which are still colonies in present times:
According to the United Nations, there are 17 non-self-governing territories (NSGTs) that are still under colonial rule:
Anguilla
Bermuda
British Virgin Islands
Cayman Islands
Falkland Islands
Gibraltar
Montserrat
Saint Helena
Turks and Caicos Islands
United States Virgin Islands
Western Sahara
Some countries that hold these territories include the United Kingdom, France, New Zealand, and the United States.
The UN has declared four decades to eradicate colonialism, with the current decade being 2021–2030. Decolonization has been one of the UN's biggest successes, with around 80 former colonies gaining independence.