What is the recommended way to interface the FAULT pin to a 3.3V logic

In the typical fault bus, the pull-up resistor is connected to the battery supply and a Zener diode is used to clamp the voltage at the MCU pin.

due to a very weak pullup current, is it possible that this current is so weak I can interface it directly to a 3.3V logic?

I recommend using a pull-up resistor to ensure the fault bus is always set to a known logic voltage.

Can the MCU pin be directly connected to FAULT, with a 10k pull-up resistor connected to the MCU's 3.3V logic?

Yes, this pull-up will set the fault bus to a logic high as the default condition. As you mentioned, the internal pull-up is very weak, so the MCU pin may be able to sink this small current. However, it may be prudent to include a DNP Zener in the schematic so that you can populate later if necessary.

The Zener could also be useful in case there are issues with the power supply sequencing, or during surges on the battery. I recommend having this option so that you can avoid a possible board revision later, as long as you have the pads available you would only need to change the bill of materials if the Zener becomes necessary.