Thanks for the great question. Typically, for any given use case, yes there might be a few ways to solve the scenario. By understanding what the various features do, you can meet nearly all your system architecture needs. Each PAAS service offers different feature sets and has unique advantages. For PAAS solutions/Apps, generally a combination of the networking features yields desired outcome. So, You don't have to choose just one of these services. They integrate with each other as well as they do with external services.
I understand you’re looking for consolidation of VNet approaches between the PaaS services, could you please share some more details on your specific requirement for better understanding? When you say, “These are often build with the specific PaaS product”, what specific build are you referring to?
Yes, there are several approaches for PAAS networking, choosing the right network feature depends on the requirement/scenario you’re dealing with:
Specific to App Service (Networking options)– Private EndPoints, Hybrid Connection, VNET, Application Gateway integration, NAT gateway and Traffic Manager integration.