most of what you see in videos and read about in threads could be confusing and seem contradicting depending upon when the video was made and when the thread was written. hopefully, everything will make more sense once you have things in front of you and begin to experiment with simple things like "everyday usage"
Typically the pin29 switch "was" used to trigger loading of the initial iso in the IPL menu (BIOS menu)...Now, with autoboot, the switch is not needed to trigger the iso since it will automatically load. Having a pin29 switch can be considered as optional depending on the setup and/or firmware used on WKF/WASP.
it all depends on how you intend to use your portable, also depends on if you are familiar with the functionality of WKF/WASP to begin with to make certain decisions as to if you need a switch or if you want to use a certain firmware...
it just takes time to play with the chip itself to get an understanding of the pros/cons for your portable build.