Hamlib supports over 200 radios. Not all controllable features are supported. Custom macros can be created using Hamlib commands, but only if that particular feature is supported. You can also use the special "w" Hamlib command in a macro to send native commands directly to a radio, but even this approach may not be supported for a particular command.
Go to RigPi SETTINGS>Radio>Advanced and use the Radio Capabilities button to show a list of all features for the selected radio supported by Hamlib.
The Hamlib library is in a constant state of improvement and enhancement. New radios are frequently added. Here is a link to the Hamlib forum where these developments are discussed: