Pod? Are you referring to a capsule?
If so, they can stay in it till they outgrow it (each capsule has different weight or height limits), then they need to go into a carseat.
You can go directly to a covertible carseat and skip the capsule part altogether. (a convertible carseat means it can face rearwards and forwards, an ordinary carseat can only face forwards) - you want your child to rear face as long as humanly possible