I have sliver and did not try to use it with sliver yet because in the page I want to use it , I do not use it yet so for who want to make footer in the bottom without staying fix (will stay in the bottom of the page until the user scroll to the bottom of the page)

body: Center(
          child: SingleChildScrollView(
            scrollDirection: Axis.horizontal,
            child: Container(
              color: Colors.white,
              // decoration: const BoxDecoration(
              //     image: DecorationImage(
              //         image: AssetImage('assets/images/backcv2.jpg'),
              //         fit: BoxFit.fill)),
              // color: Colors.white,
              height: 1100,
              width: 1111,
              child: ListView(
                scrollDirection: Axis.vertical,
                children: [
  //after all the widget in the body

                 SizedBoxFooter(),
                ],
              ),
            ),
          ),
        ),
      ),



Widget SizedBoxFooter() {
  return SizedBox
    (
    height: 29,
    width: double.infinity,
    child: Container(
// margin: EdgeInsets.only(bottom: 5),
      padding: const EdgeInsets.only(bottom: 1.0, right: 7, left: 9),

      color: Colors.white,
      height: 37,
      child: InkWell(
          onTap: () {
            showModalBottomSheet(
              isScrollControlled: true,
              context: context,
              builder: (bctx) {
                return FractionallySizedBox(
                  heightFactor: 0.47,
// widthFactor: 1,
                  child: //a column in a container , a listview - what you want
                );
              },
            );
          },
          child: Center(
            child: Text(
              strinfotxt,
              style: TextStyle(fontSize: 15.9),
            ),
          )),
    )
  );
}```