Even a dialogue like this won't have much impact because there really isn't anything we can do now to hinder or stop their Invasion.
At the moment nothing can be expected of anything because indeed when sanctions are useless then one of the last hopes is to hope they stop this voluntarily although this is indeed very difficult to happen
I think what they mean by dialogue is when two countries talk to each other and not the kind of dialogue that is happening on this thread. Maybe they have tried talking to each other already but it didn't work out well so the other country have nothing to do but started a war. We that are only regular individuals can't do much to stop the war but some of us are still finding a way to help at least, that is why we have this boycott thing.
Like sanctions, boycots doesn't have the ability to stop the war but it can only help weaken Russia. For some that are against Russia, that's better than nothing but there are some that won't support this act for some reasons.
There is no war that can be good. Of course, it is an individual matter whether someone wants to support the boycott or not. The boycott and sanctions are perhaps the most peaceful attempt help in stop the war if the aggressor doesn't want to stop it, so in my opinion this initiative is good.