Hi @solomon.squek
I've been slowly hacking on a Pong clone too 
as a means to learn Playdate development.
You might like my thread here: Pongdate - two-player Pong built with the SDK
I talk about how I used the collision system.
But maybe to answer your question directly, if you have a current position, direction, and speed, then that gives you the next "goal" for the ball... or where it's going, which maybe maps into the collision examples you're looking at?
In my Pong, I used moveWithCollisions which seemed to work and match my expectations.
Happy to answer more specific questions too! Good luck!