Always get android updates instantly A Nexus 5, for example, receives the latest android updates instantly.

Is it possible to get this pure version of android on any custom android phone (like Galaxy S3)?

Do note I DO NOT mean:


Something like Cyanogenmod. While it does eventually give latest android update it is not instant like on Nexus devices. Default google apps are also not installed out of the box or updated automatically.
A solution that keeps requiring manual install (like a custom mod maybe) everytime a new official version of android is out. I am looking for a solution where after manual intervention once, stock android will be installed and I will receive android updates instantly.
A specific solution to Galaxy S3. I'm just looking for the term used to have instant automatic updates on your device, I'm very new to Android sorry.
No. When new Android versions are developed by Google, they use the Nexus devices to test and develop them. They co-operate with the vendors of the different hardware and software components inside the device so that all the necessary driver changes will be ready for the new version, and they only announce it when the updates are already available for Nexus devices.

Google works together with the leading handset manufacturers to give them early access to the new Android version and to help them make the necessary changes to support it, but even so, there's always going to be a delay between when the new version is announced and when manufacturer updates are ready.

Third-party ROMs like Cyanogenmod are another option, but as they're made by volunteers without early access to Google's code, they usually become stable much later than official ROMs are released.

So if you're not happy with the timeliness of updates for Samsung devices (or any other manufacturer), your only option is to not buy devices from that manufacturer.