> Their main lever seems to be supreme court appointments

The President has far more power than that.

    - Veto Power: Blocks congressional bills; overrides require a two-thirds majority, which is rare.
    - Executive Orders: Directives to federal agencies that bypass Congress (limited by courts and future presidents).
    - Foreign Policy Leadership: Sole power to negotiate treaties (requiring Senate ratification) and recognize foreign governments.
    - Pardon Power: Can pardon federal offenses, unchecked by other branches.
    - Appointment Authority: Nominates not only Supreme Court justices, but federal judges, and cabinet members, shaping long-term policy and judicial interpretation.

What goes along with that is ability to get people elected (or not) by backing them, both actually and monetarily. Trump killing the immigration bill during Biden's term is a good example, and he wasn't even President (yet) at the time. I expect he'll focus on more palatable legislation during the first two years, to keep the senate majority through 2028, but we'll see.