How could I add "gravity" to a top-down shooter's bullet, such as in The Binding of Isaac?

I am currently working on a 2D top down twin-stick shooter with similar mechanics to The Binding of Isaac. One thing I've noticed in Isaac is that, although you can only shoot in 4 directions, the bullets' direction is influenced by the movement of the player, which allows for a little more strategic shooting. I uploaded a video to exemplify that, notice how I can reach areas that are beyond where my player can walk. I want to do that in my game as well, but I don't know how. Currently my shooting script looks like this:

 void Shot()
     {
         GameObject bullet = Instantiate(bulletPrefab, tipOfGun.position, tipOfGun.rotation);
         Rigidbody2D bulletRb = bullet.GetComponent<Rigidbody2D>();
         bulletRb.AddForce(tipOfGun.up * bulletSpeed, ForceMode2D.Impulse);
     }

The shot comes out of an object called "tipOfGun" that is a child of the gun object, which is, in turn, a child of the player object. The player movement is equally simple:

  private Vector3 GetMovementFromInput()
     {
         var posX = horizontal * playerSpeed * Time.deltaTime;
         var posY = vertical * playerSpeed * Time.deltaTime;
         var posZ = 0;
 
         var vMovement = new Vector3(posX, posY, posZ);
         return vMovement;
     }
     void FixedUpdate()
     {
         if (horizontal != 0 && vertical != 0) // Checks if moving diagonally
         {
             // limits diagonal movement speed to 70%
             horizontal *= velLimit;
             vertical *= velLimit;
         }        
         rb.AddForce(vMovement.normalized * playerSpeed, ForceMode2D.Impulse);
 }

The only way I can think of doing this is taking account of the player's speed and direction and adding an additional force to the bullet according to that, but I wonder if there's a more straightforward way, using physics.