Really great writeup friend. I should point out that the npx ... command will still run without the initial npm -g ... installation. npx pulls the package and runs the command without installing it globally.
Is it advisable to just use the npx ... without needing to install react globally?
Yes, Paul. npx ... always pulls the package off the registry and makes sure you always use the latest version of the package which could have fixed bugs and security vulnerabilities. So, yes, it is advisable.