Static apps are correct because they can't do dynamic processing. Separation can also use Azure Functions in addition to App Serivce. In addition to separating as pages, there is also a method of incorporating dynamic behavior into a static site by calling a dynamic API server from a static site with a client-side script using an architecture called SPA (Single Page Application).
By default it does not have the same entry point. If you want to have the same entry point, it is common to use a DNS server or L7 load balancer with a custom domain.
The simplest way is to use a subdomain, for example, to resolve "static.example.com" to a static website and "dynamic.example.com" to a dynamic website.
Alternatively, the L7 load balancer allows path-based routing in the same domain.
For example, "example.com/static" will be routed to a static website and "example.com/dynamyc" will be routed to a dynamic website. The L7 load balancer can use Azure Application Gateway and Azure Front Door.