It's hosted as a progressive web app on netlify (for free) because it's just a vue app, using the browser's local storage and indexDB APIs for data storage.
Yes sure thing, you need to build the project, and since it's a vue project only, it does not any server to process the requests or do any kind of logic, it can be run directly on the browser, and or you to expose it publicly, you have multiple choices:
I would go with Github Pages, I feel like it's much simpler (even though the other options are quite simple too), and currently using it to host my portfolio which is built with Vue and Vite, so your use case.
If you are wondering about the custom domain, you can get any domain from any provider, and tell Github to use it instead of the default github.io domain, all the choices above have this option, but I think they require you to upgrade the plan.