If you are looking to import an Rhino 6 or 7 RUI, you can do that here in Rhino 8: Go to Options → Appearance → Toolbars and pick the Gear to import a Rhino 7 RUI into Rhino 8

In Rhino 8, you can save and restore unique layouts of toolbars here. This is part of the new Rhino 8 Ui system, that is share by both Rhino 8 for Windows and Mac.

WindowLayout is also a command that you can type in.

Alias are in their own file. In Rhino 6 or 7 you can go to Options → Aliases → Export a ini file. In Rhino 8, Options → Aliases → Import. image.png

Rhino System options like Keyboard shortcuts, Modeling aids setting, Files settings and more can be saved from Rhino 6 or 7 with the OptionsExport command.

In Rhino 6 or 7, type OptionsExport or take it from the Tools menu, and write an the ini file In Rhino 8, type OptionsImport or take it from the Tools menu, and import the ini file.