You make some interesting points! But I disagree. I think the global market is a huge opportunity for Vietnamese pop music.
Vpop covers a lot of genres, from rock to r&b to hip hop to kpop-style dance music. When artists are able to embrace those different genres and collaborate with singers in other countries, you get some incredible results. For example, one group that has done well globally is BTS, which is a Korean boy band that has brought in artists from around the world: rappers like Nicki Minaj and Ed Sheeran and singers like Charlie Puth. The same thing can happen with Vpop: when Vietnamese artists release songs in collaboration with international stars, they can bring new attention to their work while also introducing themselves to more listeners.
And it's not just collaborations, it's also about production. The way music is made, recorded, mixed, and mastered all has an impact on how widely listened to it is. This means that working with people who have experience with international production, people who understand how to make something sound universally appealing, is so important when it comes to global success for Vietnamese musicians.
I think if Vpop artists take these two things into account—collaboration and production—they will have international appeal. I think the song that got most international appeal in Vpop is Son Tung M-TP's song with Snoop Dogg "Hay Trao Cho Anh". When he released that song, many people from the West commented on this MV. They didn't know the Vietnamese language but they liked the song. He has the recipe down but I think his latest English song isn't how you get international appeal. BTS didn't get big because of their English songs, they got big because of their Korean songs and all their promotional activities in the West.