Personal experience with this one. I think your recruiting office will give you the best information. I was accepted and had to do a PFA before swearing in. I’ll say I wasn’t great at running at the time. You would have to jump through extra hoops assuming you failed the PFA. If you’re in the program and you fail one just remember it’ll show on your record when you arrive at OCS. I believe you are required to do a PFA within 60 (+-) days before shipping. Personally I would advise doing push-ups sporadically throughout the day, maybe even set alarms every hour or two to remind yourself. Other things you can do for the push-ups may be adding weight and doing pyramids. From one month I had gone from 25 to 60.
TLDR your recruiter will give you the best answer, but in my experience if the Navy wants you and you can work to improve, you can make it work (I wasn’t booted but told in the most clear terms they had to see improvement in the numbers). Good luck!