What is meant by the column "Most recent release details"? If the OS has been released, why isn't it available for the device? Thanks.
Welcome to the community!
What phone or device are you using? Are you referring to an OS released by Google/Apple or one released by the phone manufacturers?
Depending on the age of your device, it may or may not be eligible for up-to-date OS releases. For example, Samsung generally only provides updates for 2 years for their devices. So while Android O has been available for a while on some devices, Samsung did not provide an Android O update for my Galaxy S5.
On the other hand, if there is an OS update for your particular phone model, you should note that it's possible that the update might only available for certain versions of that model. For example, the OS updates frequently are available for US versions of phone models before the Canadian versions.
In addition, once a Canadian version of an update is available from the phone manufacturers, it can still take a while to test and approve the update before its rollout (see here).
Hope this helps