I am looking for a 40 input OR gate which minimize PCB space
Almost no components are required.

The INA301 datasheet says the ALERT pin is an open drain output, active low. This means that it is normally high impedance, and should be pulled up to Vcc with an external resistor.  When the chip wants to signal an overcurrent, it pulls the line low using an internal transistor.

If you simply connect them all together, and share a single pull-up, then any one chip can pull the line low to indicate a fault. This will not affect the other chips. This is known as "wired OR".

You might need to tweak the pull-up resistor value a little to account for the leakage current. You definitely don't want one per chip, so don't just duplicate the recommended layout 40 times.