Depends on the university - and course. I‘m currently at TUM (CS) and you don‘t need to submit any homework assignments to be admitted to an exam. Though there are some courses where part of or the complete grade are made up of homework assignments.
Cheating is still a problem nonetheless and from personal experience and being involved with grading seems to have gotten bigger with online examinations (obv), closed or open book.
One interesting approach I saw one course do to handle online exams is to have an unsupervised open book exam with some randomization in the problem statements and then inviting a random subset of students for an oral re-examination. Basically just a 10-20 minute conversation in which you should explain how you went about answering the questions. The idea seems to be to do that often enough and you will find the cheaters who will be unable to explain how they derived their answers. I wonder if that‘s an approach that could work generally and maybe even for homework assignments though the effort becomes quite considerable then.
One interesting approach I saw one course do to handle online exams is to have an unsupervised open book exam with some randomization in the problem statements and then inviting a random subset of students for an oral re-examination. Basically just a 10-20 minute conversation in which you should explain how you went about answering the questions. The idea seems to be to do that often enough and you will find the cheaters who will be unable to explain how they derived their answers. I wonder if that‘s an approach that could work generally and maybe even for homework assignments though the effort becomes quite considerable then.