I am sticking to facts, history, archaeology, and the writings of Israel Finkelstein. So if you are wondering where I am going, that is my path.
And actually, the extent of Omride power and territory was pretty close to what the Bible claims was the extent of David's power and territory.
That's actually not a coincidence. When the northern Israelite kingdom collapsed, many northerners moved south to Judah. King Hezekiah needed to come up with a new narrative that gave Jerusalem the legitimacy to rule both populations. This is also when their religion became monotheistic in nature.
Then later, when the Neo-Assyrian Empire collapsed, King Josiah wanted to reclaim the former Israelite kingdom to the north under his own rule. And to make that claim, he needed to pretend that his own ancestors had once ruled all the territory that the Omrides once ruled.
Between the rewriting of history by these two kings, we end up with the untrue description of a united monarchy under David
that we find within the Bible.
They had the time of Saul's kingdom pushed back a century or so to make space in the narrative for a united monarchy under David and Solomon. They had Pharaoh Shishak/Shoshenq I's invasion rewritten so that he plundered Jerusalem instead of destroying Saul's kingdom. And they had the invasion to destroy Saul's kingdom rewritten so that it was instead Egypt's Philistine allies who toppled the now-much-earlier Saul.