I tried using ktor+exposed for a side project with kotlinx.serialization and had:

@Serializable
data class ChecklistResponse(
    val id: UUID, // requires custom serializer
    val name: String
)

class Checklist(id: EntityID<UUID>) : UUIDEntity(id) {
    companion object: UUIDEntityClass<Checklist>(Checklists)
    var name by Checklists.name
    val items by ChecklistItem referrersOn ChecklistItems.checklist
}

suspend fun getChecklists(): List<ChecklistRes> {
    return db.transaction { Checklist.all().map {
        ChecklistResponse(it.id.value, it.name) }
    }
}

i can then

call.respond(getChecklists())

There are probably nicer solutions but it works well enough and by having the response class separately I can provide a consistent API when I need to make changes to my DAO.

Issue on exposed https://github.com/JetBrains/Exposed/issues/497

Aha....I have to manually serialize it

Thanks a lot for your help