Upgaade backend in nodejs and App in flutter

@@@@@@@@@ READ WELL BEFORE BIT @@@@@@@@ We need a programmer that can work in the node.js backend and that adds there pigeonholed to be selected by the owner as, chicken, pack or pound, that 2, which the user to add to the cart appears in a blue bubble the quantity selected by the user 3, what price we can set if it is per pound, package or whole. all this has to be done in the backend and then update on the page and in the app ..... if you are not an expert in node.js or expert in flutter please do not apply this is an urgent job we not have time to lose, we can t accept a subcontract we will hire a direct programmer.