Thank you so much. Now it makes more sense to not get the passport stamped. According to our current timeline, we won't get anything approved until the end of 2024. Canada specifically states that you can travel with an expired GC and an extension letter, but that's the only country that allows it. We actually want to travel to the UAE, Mexico, and, if possible, Costa Rica. However, these countries generally require a valid GC to enter, so we're not sure if they will accept the extension letter from USCIS