Aside from echoing what everyone else is saying -- that this is a blatant attempt to rip you off and you shouldn't go anywhere near it -- I just wanted to point out that it is in no way "standard" to have an NDA under these circumstances anyway.
In my entire career (over 20 years writing software for money) I have never signed, or even seriously considered signing, a full-on NDA. Doing so can be extremely dangerous to your future career, not least because potentially it will no longer be safe for you to work in certain fields, and you don't even know in advance what those fields are. At the same time, it has basically no upside for the person committing not to disclose. It's not unusual for employment or freelance contracts to include some clauses about not disclosing trade secrets learned during the gig, but even then there ought to be explicit limits on the scope of any restrictions, as well as other safeguards for the employee/freelancer.
If you're dealing with a really big player, and you're a little player trying to break into a market where you need access to their technology, then accepting their NDA terms might be an unavoidable price of admission where you have no real alternative if you want to play the game. I struggle to imagine why you'd consider signing one under less demanding conditions, though.
The situation described here is not even close to that kind of relationship. It seems more akin to the situation where Idea Guy thinks his idea is so amazing that Technical Guy should be willing to sign anything just to know about it. But try that on any veteran Technical Guy, or any serious investor, and Idea Guy will get laughed out of the room. In this case, it makes even less sense, because it sounds like any relevant information has already been shared anyway and there is literally no upside at all to signing anything like this.
There also seems to be some sort of presumption that OP would be the subordinate in any relationship and the other person would be senior. It's not clear why that would make sense from what we've been told so far, because it sounds like the OP has been the one doing most/all of the work so far. However, business people sometimes forget that good technical people aren't under any obligation to work for peanuts, and then they make unfounded assumptions about how they should obviously be the senior player in any deal. A counter-offer where they only get to have a minority share of the equity in a new company owned by both people, or even where they are reduced to being an employee of a company founded by the technical person, may provide an effective reality check in such situations, because without the technical person's work it's entirely possible that the business person has nothing of value to build a company around.
On the bright side, there is at least one useful lesson here, because it has provided an excellent demonstration of one of the most reliable indicators that you you don't want to engage in any sort of business relationship with someone. :-)