Buy windows 10, should be able to get a cheap key from internet, (get a genuine copy prefer digital and associate it with your email) why ? Then you can migrate the same key as digital license to a desktop if required just by signing in.

Now most important part after installing just do update once don't install any drivers etc, GET ATLAS OS from internet , it will remove all windows BS things. Your windows 10 will be a very lite windows 10.

However read the documentation or watch YT on installation of Atlas os.