I'm learning Android development, trying to do code a simple app. Want to load a JSON file on the assets folder into a string in ViewModel (livedata). Can someone point correct way to load the JSON data (user, id:Int + name:String), shall i use GSON (looks its "old), Moshi (newer) or something else?

I'd suggest kotlinx serialization or Moshi, not Gson

kotlinx.serialization has worked well for me so far. It’s also multiplatform if you ever decide to go that route.

The main reason you might want to avoid Gson -- in kotlin specifically -- is that it isn't null safe. It will happily put a null in your non-null properties, which will crash as soon as you try to access them.