Nest Protects are wireless so would not comply to the new requirements, it seems.
There are however zwave/zigbee audio listeners that would listen to the alarm out of smoke/CO detectors. I just don’t know whether the alarm in Scotland would sound the same as in US, for the listeners to work. I know this only because I saw something in another thread recently.
Also note the alarms for smoke and for CO are different, at least in US. Search YouTube and you probably could find how they are different.