Any movement can be done external or internal, styles are there as tools to use to build yourself. Everyone starts out as a external practioner, some styles will make it easier or harder to complete your transition to internal.
Wing Chun is one of the easiest simple methods to make that transformation to a internal aspect, if practiced correctly.
Some styles will never leed you to internal, like boxing, MMA, Karate ect., their just based on building the muscles and speed.
Styles like Tai-Chi will leed to internal, but the tools are not simple and very few get there using the form method that is being taught by most teachers these days. If the teacher does not have it, they cannot teach it to the student.
So just learning the forms is the external part, making the forms internal is the hard part.
If you can get the internal from doing one of these styles (tools) then you can apply it to movements of boxing ,MMA , Karate ect..
So yes Wing Chun I think is one of the most direct simplest method to build your house. You will still need the guidence of one that can show how the tools need to be used or else you will always just being doing external Wing Chun.
From what I have seen most people are mostly learning external Wing Chun and are unaware of the difference.