Yeah, optimally the app should have been global from the first place. For example if we consider the second wave of the epidemic, which in Finland showed signs

Yeah, optimally the app should have been global from the first place. For example if we consider the second wave of the epidemic, which in Finland showed signs of starting (but hasn't really started) straight couple of weeks after travelling abroad opened to several countries and then when the travel restrictions were put back on etc. immediately the contaminations went down again, so they were mostly just coming with people coming from abroad. Perhaps those peoples possible contaminations would have been possible to target already way before with a global app.