Timing chain? Unsure issue

So I've been doing the searches and keep reading about the same issues and struggling to find my answer (it's probably there somewhere but with 1300 google results I wave the white flag)

Our second commodore, a 2004 VZ acclaim wagon started an odd timing chain rattle a couple days ago, never done it before. It started rattling at cold start and continued, increased in speed related to engine revs, stopped engine and was still there, there is no engine codes, and there is nothing out of place. After a while, the amount of time varies, it goes away, and it doesn't happen every start, but it does happen when it's warm sometimes as well and these are all the parts that confuse me.

I would have thought if it was a stretched chain it would happen every time it started and would either go away after a short while or stay continuously, and I've read of a few people that have tensioners break and that has caused massive issues including car not starting but we have a running car with no loss in power. One thought I had was maybe a blocked or gunked up tensionor but unsure. Maybe oil pump or oil pump chain? Any thoughts or suggestions?

And with that, if I'm going to strip front of engine down, should I just change the chains, tensioners anyway? What about oil pump?