Red Squirrel
No Lifer
This is why I like to never finish the ceiling in a basement, if you want a finished look do drop ceiling. Makes it so much easier to add something upstairs in the future like data drops, power etc.
From upstairs then you just cut your outlet hole (for power I like to go against a stud so I can screw it in from inside the box) and drill down to the basement then you can run wire that way. This should work for plumbing too, but now you have an unwanted hole in the wall but in the case of a bidet you'd want an outlet too anyway so do the plumbing first through the square hole you created then electrical after. Long drill bits are handy for this type of work.
From upstairs then you just cut your outlet hole (for power I like to go against a stud so I can screw it in from inside the box) and drill down to the basement then you can run wire that way. This should work for plumbing too, but now you have an unwanted hole in the wall but in the case of a bidet you'd want an outlet too anyway so do the plumbing first through the square hole you created then electrical after. Long drill bits are handy for this type of work.