I would buy some corporate WordPress template and do all of my content management there for sanity and quickness, it's also good for SEO. As for the web application, I would code that myself from scratch using Node and React. For the back end, an API built with NodeJs and Express would be quick to do. I would secure it with the jsonwebtoken library to avoid touching the database too much. Then for the React client, I would import Ant design components, which has a large collection of customizable components that have a corporate look by default, it also has great docs and it's easy to use. For the hosting, I would get a VPS and a domain. The user enters my domain and the first thing to be seen is my Wordpress site, if the user needs to use the web app, then a subdomain points to it. That way, everything lives in the same place. A VPS with CyberPanel would provide an interface so you can view your files and configure your website's ssl quickly without using the terminal too much.
