From first glance it looks like InstallInstructionsorBanner needs to be reworked to include the isMobile variable within it's logic. If everything else is working that should do the trick, if not I would look over the service worker, verify that everything is setup correctly, if you're still having trouble feel free to debug through and give me some feedback and ill get back to you with an answer.

const InstallInstructionsOrBanner = () => {
  const userAgent = window.navigator.userAgent;
  const isIosDevice = /iPad|iPhone|iPod/.test(userAgent) && 
!window.MSStream;

if (isIosDevice) {
  return <IosInstallInstructions />;
} else {
  return <InstallBanner />;
}
};

you should simply be able to rework the if statement