It all depends on what the meaning of “offline” is… 
We are actually discussing two very similar but different things in these threads:
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The LifeHackster method - where the cam and the viewing phone do have internet access and do authenticate with Wyze before going offline, and do remain continuously powered after authenticating with Wyze. This still works. - see below.
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The @kyphos Norwegian fjord method - where the cam and the viewing phone do not ever have internet access after powering on and do not authenticate with Wyze before going offline. This no longer works.
Method 1 was actually an involuntary discovery for me when a battery backup kept the Wyze cams running and recording just fine to their SD cards during an extended internet outage.
Also, minutes ago, I just verified it again by unplugging my main internet router, but leaving the home mesh up and running.
So all cams were authenticated with Wyze, and are still on the WiFi LAN, but no longer have any internet connection.
Both an Apple iPhone and an Android phone were able to view the SD card recordings and view the live stream - verified by me walking in front of the cameras while watching on the phone.
The only “trick” was that I had to open the Wyze app with cellular data ON to authenticate the phone, then I had to turn cellular data OFF to force the phone to talk to the cams by the local WiFi LAN only.
So, while the @kyphos Norwegian fjord method sounds wonderful, especially when travelling beyond any cell phone coverage, it apparently stopped working just before I arrived in the Wyze community.
The LifeHackster method is more limited, but still works and can be quite useful - just as long as you have continuous power for the cams and some cell coverage with a phone or mobile hotspot when you need to interact with the cams. 
And I think this is one thing the WCO is supposed to offer - off grid time lapse and scheduled recording to its SD card, plus phone viewing.