In my experience serious students of martial art should not waste time on such silly notions and know internal and external are false categories that show up in 1669 (in the the Epitaph for Wang Zhengnan) more as a protest against the Qing Dynasty by Han people than anything else, and there was no mention ot Taiji, Xingyi or Bagua in it at all. And prior to that there was no such delineation, because it did not matter.
Also Chen Fake (1887ā1957) never thought about internal vs external, he just trained and taught his family style, what we now call Chen Taijiquan. And last there is an old CMA saying...internal goes to external and external goes to internal. This means that if trained properly, they end up in the same place.
To me, a guy who once argued for these ridiculous categories, such categories are at best elitist or at worst an excuse. I'm a taiji guy I use to be a Xingyiquan guy, that is all.... and speaking as a xingyi guy on the topic of internal and external (and I am betting you would get this from many Xingyiquan people)..... who cares..shut up and train.