If your driver door lock spins with "no joy", you can rebuild it with some OEM parts. There is a guy (in Turkey) who sells them on Ebay. I bought them and did the whole project in under 30 minutes. Then I fixed my key remote so I woudn't need to use the door lock that much

Door handle: is your problem with the outside handle (an known X5 problem, buy the parts and replace) or inside?

Passenger window. Likely the window regulator, but there is good material on the forum on parts that fail and how to replace them.

Keep going, you'll get the typical X5 issues sorted and have a fine luxury car for MUCH less than new.

Sustainable development is keeping a good car on the road rather than buying a new one.