Earliest date to file N-400 is in early 2027, so still a long ways away.
The last two pages have the biographical information of the applicant, plus a page where a USCIS official will sign, place a photo of the applicant, and stamp it. Then it's mailed back. Not much to do is correct, but it looks like the NOA itself is not good enough for state agencies that require it: the returned form is required.
Application was just mailed to the Dallas lockbox today. I'll be sure to post updates.