You can add any type of data you would like to mSecure. One of the best things about the app is that it's extremely flexible, so you can create new templates to store data, or you can use existing templates and just add extra fields to it. Have you tried to add your homekit codes to a record in mSecure yet? If so, what is causing problems for you?
That would be nice, if we can add codes of our homekit appliances.