Difficulty installing Google Tag Manager in React for Google Analytics
You can add that script in /public/index.html since its a single page app but will only load once unless you add events depending on what your Google Tags do.
To implement Google Tag Manager, use NPM package for more customizable options: https://www.npmjs.com/package/react-google-tag-manager
If you're using Google analytics within your tag manger, read below.
Best approach is to use Google Analytics React NPM Package: https://github.com/react-ga/react-ga
Add: ReactGA.pageview(window.location.pathname + window.location.search); in your router change to make sure you get your page hits.