But would Israel mind shifting the burden of feeding Gazans from UNRWA *and itself* to the U.S.? Once U.S.-led airdrops start in earnest, won’t America “own” feeding Gaza? And won’t Israel have that much more leeway to keep land crossings closed (and under effective control of settlers)?

I find it hard to believe anyone seriously thinks the US can take that role in anything but a temporary stopgap. And even that is mainly PR. Beyond food aid, UNRWA is a huge operation - also in the West Bank - which cannot be replaced.