Show the game to the Defold team as it nears release. Their policy is to consider making console targets when there is actually a worthwhile game to publish on it.
Keep in mind supporting Switch costs money. You have to spend several k minimum to buy development consoles which you need to have to release Switch games.
If you do have a finished game it would be best to release on say Steam first which costs only $100 and that cost can be recouped once you sell enough on Steam. Then you can have a decent idea if releasing on Switch is even worth it.
I agree that Switch support would be great. I’ll have Defold based games finished in the future which I’ll want to publish on it too.