要从Android Paging 3的PagingData对象中获取数据列表，可以按照以下步骤进行操作：

1. 定义一个PagingDataAdapter适配器类，该类继承自RecyclerView.Adapter类，并使用PagingData作为数据类型。

class MyPagingAdapter : PagingDataAdapter(diffCallback) {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        // 创建ViewHolder
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        // 绑定ViewHolder
    }
}

2. 在Activity或Fragment中设置RecyclerView和适配器。

class MyFragment : Fragment() {
    private lateinit var recyclerView: RecyclerView
    private lateinit var adapter: MyPagingAdapter

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = inflater.inflate(R.layout.fragment_my, container, false)
        recyclerView = view.findViewById(R.id.recyclerView)
        adapter = MyPagingAdapter()

        recyclerView.adapter = adapter
        recyclerView.layoutManager = LinearLayoutManager(requireContext())

        return view
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        // 观察PagingData对象的变化，并提交新数据到适配器
        viewModel.pagingData.observe(viewLifecycleOwner) { pagingData ->
            adapter.submitData(viewLifecycleOwner.lifecycle, pagingData)
        }
    }
}

3. 在ViewModel中创建PagingData对象，并获取数据列表。

class MyViewModel : ViewModel() {
    val pagingData: LiveData> = liveData {
        val pagingSource = myPagingSource()
        val config = PagingConfig(pageSize = 20)
        emit(pagingSource.flowable
            .cachedIn(viewModelScope)
            .asLiveData())
    }

    private fun myPagingSource(): PagingSource {
        // 创建自定义的PagingSource对象，用于从数据源获取数据
    }
}

通过以上步骤，你就可以从PagingData对象中获取数据列表，并将其展示在RecyclerView中。在滚动RecyclerView时，Paging 3库会自动加载更多数据，实现无限滚动的效果。