UK to use Apple-Google API in NHS contact tracing app

I was watching the daily update at the time and as usual with the current UK government, it was framed in a way in which they were taking credit for the initiative. The technology will soon be baked into the OS on our phones and from the specs, the APIs Apple and Google are putting together look very promising.

It's great news, but it wasn't communicated correctly. What if your phone cannot be updated to run the latest version when these changes are available? Android especially, which has vendor and network versions that are either slow to be updated or not updated at all.