Pre-employment screenings usually consist of a urine screen for drugs and possibly nicotine. I'm pretty sure Scoliosis won't show up on the (tongue in cheek....).
An employer can put in a job description that you are required to lift so much and other physical requirements. As long as you say you can do this and you do not have a doctor saying you can't, then you are they should hire you (assuming you are the candidate they want.) That also means if you come back later and say you cannot do those things, they can fire you. Or they might be able to successfully fight a Worker's Comp claim if you injure yourself on the job. They could state that you took unnecessary risk in regard to your health condition, didn't disclose, etc.
But an interviewer can choose not to hire you for any reason whatsoever. It could be because of a vibe you give off, how you answer a question, how you are dressed, etc. So legally, they cannot discriminate against you because of the scoliosis, but that doesn't mean they have to hire you.
I say you need to be honest with yourself. If you think you can truly do the job, including the physical aspects of it, then go for it. If you are only going to be causing yourself more pain and more debilitation down the road, nursing is not the right choice. Don't worry about the employer, worry about yourself.
If enjoy science and the pre-reqs you are taking, consider something like becoming a lab tech or a pharmacy tech. Those jobs may require standing and some lifting, but not pulling patients up in the bed, turning and lifting patients, having patients fall on you, etc. If its the care-giving, what about occupational therapy or speech therapy? Audiology? Respiratory therapy? I'm thinking there isn't as much lifting, pulling, etc with those jobs either.
Nursing is a physically demanding job. Lots of nurses with healthy backs and knees end up with injuries and debilitation. It sounds like you are willing to do the work, but is it really the best thing for you?