The events aren't remotely comparable in terms of background, the events themselves, or what led to the events. If you can't see the difference between protests against state-wide lockdowns including curfews, restrictions on freedom of association, travel bans, etc and a group of people rioting to contest an election result all it shows is that you are so biased to the point that your opinion isn't worth considering in a serious discussion about events in Australia relating to the response to the pandemic.
There are potential defences of Australia's response (although they are increasingly seen as apologetic at best, or an outright defence of human rights abuses at worst) but saying the protests are in any way similar to the US capitol attack is not one of them.
You said:
> Police going door to door in NSW/VIC investigating protestors against lockdowns months after they have occurred.
Police are not going door to door. So, that part is inaccurate.
Police are investigating someone suspected of an offence. It's hardly unusual for it to take police months to conduct investigations.
The second one it's pretty clear they were.
I don't know which protests they were, but a number of anti-lockdown/vaccine protests were violent, which is likely the reason the police were investigating. That it's months later is almost certainly because police have been going through a shitload of leads.
The same thing is happening in the US where people suspected of participating in the January 6 riots are/were being investigated months after events.