usually I think of diagonal flying where upper body pushes your body one way and lower body blocks your lower body the other way. and then various throws are just "steering wheel" on upper, leg block/trip/reap on lower. all fine and good. can be done with "brute force" then refined.
I think it's more interesting to see split as making someone's mind/body to commit one way, and the "split" of energy happens because his mind then tries to stop and go the other way, but the body can't do that so in some cases it's going to lose balance. so you have things in sports like this:
That example is famous and "no touch" but there are various push hands like contact things that happen where you can off balance or make someone fall (like with spins) but without an explicit throw or trip.
This is useful in this sport context if you can make people do this because
1. if I applied diagonal flying or some throw in this sport, it would be a foul, plain and simple.
2. if you can make them fall down or even just split their body and mind, it's easy to go around them
3. people will to some extent use a little pushing and pulling on you so if your "push hands" is a little higher level / more subtle, you can "ward off" or do whatever and get on with it.
4. the more you get them to try to "follow" you, the higher chances you can try to "lead to emptiness" because now their commitment to the "attack" will be higher and harder for them to overcome when you are "not there".
5. there is no need to deal with all the bullshit and baggage and non stop male pattern lecturing ( ignorant man-splaining) people bring to ph.
I do not think this is "internal" but it's an interesting step.