AskHistorians

Mass deportations were considered multiple times by the Nazi Party before they settled on extermination. The issue the Nazis had is that they had nowhere to deport them to - it's one thing to tell a country "These are your citizens, you have to take them back"; it's another to say "These are our citizens, you have to take them". Not as a matter of moral right and wrong, but of legal obligation. The former is much more compelling to countries than the latter.

There was considerable talk of expelling German Jews, and many German Jews were turned away from other countries because other countries had no desire to take in large amounts of refugees - and antisemitism exacerbated that issue. The US took in a pitifully small amount, being in the midst of one of our intermittent outbreaks of anti-immigration hysteria + the Great Depression, and other countries often did even less than we did. The Sovs under Stalin refused all Jewish-German refugees. The ambiguous British position and lack of enforcement led to large amounts of Jews fleeing to Palestine - illegally, but the British made only token attempts to stop them.

Hitler spent a large amount of the 30s locking up his domestic enemies, long before death camps were conceived. Some in ordinary prisons, others in work camps.