He needs to spend the next 6 months putting his immunity to work. First, write executive orders eliminating all student loan debt, all medical debts, ensuring freedom of choice in all states, and dedicating another $100 million to ensure the defense of Ukraine. Then, he can get really crazy and remove Alito and Thomas from the Supreme Court and place two people in their spots. Probably should remove the Trump appointees as well since he was clearly a compromised President and none of his choices should have been allowed to stay. Also, add 4 more seats so the number of Supreme Court justices matches the number of Appeals courts. Each appellate court should have a representative on the Supreme Court. Also, with another executive order he can impose term limits on court Justices.
Sure, almost none of that would hold up to Republican challenges (except the stuff that challenges the immunity stuff), but it would keep them really busy over the next 6 months.
Immunity doesn't grant him extra powers it just grants him the ability to commit crimes in certain circumstances.