Perfect doesn't exist. At least in web accessibility.
You'll always find another edge case or some assistive technology user whose experience you haven't accounted for yet. Chasing that is pointless and can only lead to frustration in the team.
But better is absolutely achievable by next sprint.
No matter where you are right now, you can be in a better position in a week's time.
Add alt text to the images that don't have it. Fix that colour contrast issue on the buttons you've been putting off. Make the form errors tell people what went wrong.
None of these are going to make everything perfect. But all of them are better.
You've been using perfect as a reason to do nothing. It became an excuse. Get rid of it.
Ship better. Then ship better again.
Every small better gets you closer to perfect. Your product that gets a little more accessible each sprint looks radically different after a year. It's not perfect, but it's a hell of a lot closer than where you started.