2300 Day Prophecy
Although the study of the “Seventy Weeks" prophecy is a broad 490 literal year prophecy (70 x 7 days = 490 days) as mentioned in Daniel 9:24-27, Daniel 8 provides additional supporting evidence towards understanding the Daniel 9 prophecy (but probably not the way you are thinking):
Daniel 8 clearly speaks of a RAM with two horns (metaphorical language about a nation with two kings)… and that this RAM was at war with other surrounding nations (other beasts). The vision expands further detailing a GOAT nation attacking the RAM nation (that has two kings)… and won against the RAM in battle. And after winning, the ‘light’ of that RAM nation fell causing turmoil among the people… and that this turmoil would last 2300 days (Daniel 8: 1-14).
Fortunately, the passage explains the vision: confirming that the RAM is indeed two united nations Media & Persia (v20), and the GOAT is Greece (v21)… and after winning a battle, this King created new legislation that caused serious problems throughout the Kingdom…. so much, that Daniel nearly fainted, realizing the effects of this ordeal that was coming upon the people (Dan 8:22-27).
If we are to assume that the translators have interpreted “eleph’ shalowsh me’ah ‘ereb” correctly to mean “two thousand three hundred days” (2300 days), then this equates to just over 7 years that this turmoil period would last.
And here’s where it gets interesting, because these seven years fall EXACTLY within the Book of Ezra:
When King Cyrus died in 529 BC, King Artaxerxes (and the unmentioned King Cambyses) took leadership of Persia, and unfortunately 'inspired' multiple wars against the surrounding countries… multiple wars!!! (aligning with the Daniel 8 vision). So intense was this period, that there were several 'Pirate Kings' (from other nations) that tried to overthrow Persia, but only one (known as Gaumata) succeeded. Subsequently, this Armageddon duration lasted a 'silent' seven years (i.e. the Book of Ezra does not unpack the darkness of this time), until King Darius came to the throne and brought "peace” back into the Persian Empire in 522 BC.
In summary, the 2300 days is in fact related to the “last week” of the “Seventy Weeks Prophecy” describing the horrific period from 529BC to 522BC. You can confirm all of this by the reading public knowledge resource https://en.wikipedia.org/wiki/Cambyses_II as well as the Behistun Inscription (https://en.wikipedia.org/wiki/Full_translation_of_the_Behistun_Inscription) and the writings of Herodotus... but of course, let us not forget the Book of Ezra that describes the events prior and after this horrific event.