"MY mothers-in-law estate nor my estate is going to be large enough where there will be an estate or gift tax problem."

It isn't clear if you are trying to consider gift, estate, or both, though. Your mother-in-law can have a condo worth $500,000 FMV, which is well under the estate limit, but exceeds the gift tax exclusion for you, when gifted to your son. If you deed it as POD, he gets the benefit of the step up and there is no gift tax consideration or reporting at all in this scenario. If you wait to inherit it, then give it to him, you created more trouble for yourself than might be necessary. While you get a step up in basis due to inheritance, that's a different issue than exceeding the gift tax exclusion for the value, which is $16k for 2022 and $17k for 2023.

And you don't really know when the property will transfer by death. "Individuals taking advantage of the increased gift tax exclusion amount in effect from 2018 to 2025 will not be adversely impacted after 2025 when the exclusion amount is scheduled to drop to pre-2018 levels." By then, this condo might have significant impacts on your estate plan, because your own estate might be higher by then, as well.