No. (simple answer, keep reading for details)
(images via PKHeX save editor)
It should display an option to change it from normal to alola, but it doesn't. Therefore confirming Alolan forms (currently) aren't coded into the game. Same thing happens when trying to make galarian forms.
However, items from Alola and Galar such as Z-Crystals or Dynamax Band (also Mega Stones) are coded in. (top image is Mega Stones, middle image is Z-Crystals, bottom image is galar items)
I'm guessing these unused items are leftover from some kind of base game they start with to make newer games from (to make coding easier/faster). I doubt they're intended for a future update.
Also, sorry for the huge images. I tried to shrink them, but since they're so pixelated it only made them impossible to read. :P