I do not know what
AltGr is.
Alt+>?
In general I avoid Alt+ keyboard shortcuts because of the tendency to trigger display of ribbon tooltips.
Use the keyboard to work with the ribbon - Office Support
You can have sequential keyboard shortcuts, yes.
Ctrl+9,H would be Ctrl and 9 pressed together followed by H.
Attached is a sample document with five shortcuts all following from
Ctrl+9. These are shortcuts for insertion of symbols rather than macros but the same process applies. When creating the shortcut, start by pressing the trigger key, i.e., Ctrl+9, then press the finishing key, i.e., h. It will show
Ctrl+9,H as the keyboard shortcut. Note, it shows an upper-case H rather than lower-case even though lower case is used. With the diamond, I did two variations to show this. The one with true upper case is displayed in the dialog as Shift+D; the lower-case version simply shows D.