Is there a way to make a infinite scroll for GridView in Flutter?

Yes,
you can achieve, Please check the below is code. Please try that code and inform me, is it works for you?

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  ScrollController _scrollController = new ScrollController();
  bool isLoadingPosts = false;
  List<ImagePost> imagePosts = [];

  @override
  void initState() {
    super.initState();

    // Add a listener to the scroll controller to detect when the user has reached the end of the list
    _scrollController.addListener(() {
      if (_scrollController.position.pixels == _scrollController.position.maxScrollExtent) {
        // The user has reached the end of the list, so load more posts
        _loadMorePosts();
      }
    });
  }

  @override
  void dispose() {
    // Dispose the scroll controller when the widget is removed from the widget tree
    _scrollController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return GridView.builder(
      physics: BouncingScrollPhysics(),
      controller: _scrollController,
      padding: EdgeInsets.only(top: 3),
      gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3),
      itemCount: imagePosts.length + (isLoadingPosts ? 1 : 0), // Add 1 item for the progress indicator if isLoadingPosts is true
      itemBuilder: (BuildContext context, int index) {
        if (index < imagePosts.length) {
          return PostCard(
            imagePost: imagePosts[index],
            imageUrl: imagePosts[index].imageUrl,
          );
        } else {
          // Return the progress indicator at the end of the list if isLoadingPosts is true
          return Center(child: CircularProgressIndicator());
        }
      },
    );
  }

  // Load more posts
  void _loadMorePosts() async {
    if (!isLoadingPosts) {
      setState(() {
        isLoadingPosts = true;
      });

      // Load more posts here

      setState(() {
        isLoadingPosts = false;
      });
    }
  }
}

In the above code, We have used the ScrollController That Listens for when the user reaches at the end of the list. When the user reaches at the end of the list, we set the isLoadingPosts flag to true and load more. we show the CircularProgressIndicator at the end of the list/post. we set the isLoadingPosts false to update the widget tree to show the new post