I ran into this issue as well as I wanted to share some of my more elaborate breakpoints with people in my team.
Project with CocoaPods
You will find the xcdebugger directory in
PROJECT_NAME.xcworkspace/xcshareddata/xcdebugger
Second, you will need to make the breakpoint a shared breakpoint by right clicking the breakpoint and clicking Share Breakpoint

You should then find the Breakpoints_vX.xcbkptlist file with your shared breakpoints in the xcdebugger
Project with no CocoaPods
You should find the xcdebugger directory for the shared breakpoints here
PROJECT_NAME.xcodeproj/xcshareddata/xcdebugger
In there you will find the same breakpoints file you seek. There is also a xcdebugger directory in the xcuserdata/USERNAME.xcuserdatad but they might have some coded file paths that would be problematic when sharing other devices.