I'm sure you're likely to be adding .NET Core 3.1 support soon, but I also request that the Desktop Runtime version be added (this is the thing that allows you to write WPF/WinForms apps with .NET Core 3.x). With .NET Core 3.0, this was a separate installer. With 3.1, it appears to be a superset installer that installs both .NET Core 3.1 and the desktop runtimes.
I have added this on our TODO list together with your recommendation of adding the Desktop Runtime version as well. This improvement will be added in a future version of Advanced Installer.
I will update this thread as soon as it will be added.