I am trying to understand the amount of unique visitors who saw a specific page on my site for the first time, not within their 1st visit. How am I able to create a segment that would show me by unique visitor the amount of visitors who saw this page for the first time?
ex: Page A has 20,000 unique visitors, and x amount of those unique visitors visited for the first time.
This would require a large lookback window, since the number you're looking for requires the entire history of each visitor to be taken into consideration. In order to calculate if a user saw this page for the first time, we have to know that visitor's entire history (which could go back years).
There might be some hacky workarounds, but I don't think it's feasible to get an accurate measurement of this number currently.