My Panasonic Lumix FZ82 has a built-in intervalometer, and stop motion, slow mo video, WiFi and Bluetooth remote control, and a lot more. Plus a 60* optical zoom. All for about $350 these days. Its a great daily-driver camera.
Besides people were doing long exposure since like forever with great success. If the sensor overheating was a problem, it would make sense to introduce a hard limit and some cameras have them, but from my experience the likely reasons for the prevalent 30s are: 1/ most people don't do several minute exposures 2/ they need to sell remote triggers to somebody.
30s limit was there even during nineties when you could do hours on film without overheating anything.