turn a dict that may contain a pandas dataframe to several dicts
I'm assuming that the code works as intended.

Firstly, let me tell you that your code looks very pythonic - this is a huge plus.

My comments:

Introduction

You state that


  I have a dict that may be 'infinitely' nested 


Keep in mind that since you seem to be doing recursive calls your stack is limited hence is your ability to retrive nested dict. 

map_keys_by_type 

Argument d is not informative, try using dic (if you want to follow your change type->typ) or dictionary. 

Although, this is not extreamly important you might consider changing p to something more informative. When I've read the code first time I almost immediacy forgot what this variable stands for. However, as I said this is not very important because the function is small. 

nested_get

This bit

for k in nested_key:
    internal_dict_value = internal_dict_value.get(k, None)
    if internal_dict_value is None:
        return None


in my opinion would be clearer if you did:

if k not in internal_dict_value:
    return None
else:
    internal_dict_value = internal_dict_value[k]


not in shows your intention directly.

Everything else looks okay for me.