Where are "apps stored" if I want to launch with other apps

Since my windows days, from time to time, you need to launch a file with something besides the default app.

In KDE, you can right click - Open With - drop down to Other Application

However in windows you would navigate to Program Files and try to locate the executable.

I'm lost on how to do that in KDE. If I go there I can see 8 or 9 relevant apps. There is a button called "Show All Install Applications," but that just expands the list to 24 apps, and most of them are...weird options (like games are there).

There is a button called "Choose Other," but it takes me to my home folder. I am unsure how to navigate the home folder to find the right app to launch a file.

Can someone guide me on this?