In an extenuating circumstance, one can say the night time K'riyat Sh'ma until Netz, as per this statement:
If one didn’t say it then, make sure to complete it by Chatzot (midnight) and after the fact, one can still say it until Olot HaShachar. If one was in extenuating circumstances one may say it until HaNetz HaChama. (S”A 235:4-5, Mishna Brurah 235:27, 30)
I found in M"B 239:29
אבל בנאנס אפילו אחר שעלה השחר רק שהוא קודם הנץ נמי קורא ויוצא
The earliest time one may say Sh'ma in the morning is (under extenuating circumstances), is discussed here.
The earliest time for shema or Brachot shema is when one can recognize an acquaintance from 4 amot away called Mesheyakir, which is one hour (in Shaot Zmaniot) before HaNetz HaChama.
If the case could be established with such extreme circumstances that someone could only say Sh'ma before Netz, and he would not be able to say it later, and was not able to say it beforehand, could that one recitation count as both his night time and his morning saying of the Sh'ma?
I know that (according to the same Halachipedia site) Sh'ma said before bed can, in limited cases, count as both the Sh'ma al hamita and the evening Sh'ma so there is some (not strictly parallel) precedent for one recitation to fulfill 2 obligations.