Replacing the AMS1117 regulators on the ESP32 modules was a wash-out. I had two board with what I hoped were just burned out AMS1117 regulators. On one board, replacing it made no detectable difference. On the other board, I heard some snap-crackle-pop for a few seconds, and then smoke appeared. So, I'm giving up on that idea. I've got a small quantity of AMS1117 chips for some future project.

My 7805 regulators arrived. I've breadboarded one of them to power an ESP32 through the 5v pin. The ESP32 is running the ventbot firmware. Except for not connecting the BMP280 over I2C, this is exactly what will be running, so the current draw should be pretty close. I've already had it running for 15 minutes or so. With my finger, I can feel some warmth on the 7805, but nobody would reasonably call it "hot". So, I think I won't need to worry about a heatsink for the 7805 for this project. Yay!