I was watching some old walkouts and I saw that in 2021 players walked out with flags, it's fairly common to in sports and in other esports.
I think it's generally a good thing to tap in to, since sports culture is somewhat nationalistic and that makes people more passionate about their teams (just ask kanyefan)
I know riot has this thing about tiptoeing around anything mildly controversial, but as long as players represent their home country I don't see why not