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...it looks like the paint and graphics are in pretty good shape, under the grease and dirt. That's a plus, and adds value (if you're looking for a project like this one.) Also, it looks like everything is still there, in terms of the components. Also a plus and adds value. Negatives are that it needs complete dismantling, cleaning, and reassembly with fresh grease, new rubber (tires, brake blocks, probably the brake lever hoods are shot.) New cables and housing, maybe new bearings (those are cheap), new chain, sort of up in the air whether stuff like the freewheel still works OK. There are a lot of ifs.
The wheels are laced with tubular rims. That's an extra hassle on my projects, because I just don't use tubular tires any more. So either you get used to mounting, gluing, and sometimes replacing tubulars, or you have to relace the wheels with clincher rims. For me, that's a minus, and lowers value (what I'm willing to pay for a project bike.) I can't imagine you could make any money.
Legnano does have some collector value. I'm not sure how many collectors are still breathing (and collecting). It's fewer than it was ten years ago.
Mostly, don't get involved with it unless it's exactly the right size frame for you. It's a lot of work, as a project. (Although less than stripping, repainting, and restoring the box lining and decals on that frame.) The Reynolds 531 ones are interesting. I've had one of each (Reynolds tubing and the other stuff they used ...Falck maybe ??). The Reynolds frame tubing was an upgrade, and it cost extra.
You can look at the various articles and links on the condorino website for more info.
https://condorino.com/legnano-timeline/
I paid about 400 bucks for one that I had to do a similar overhaul and wheel re-lacing for about ten years ago. I think the one I bought had a few components missing, but they weren't that hard to find. Probably worth a little less in today's market, unless you sell it some place like e-bay. If it's your friend who now owns it, figure out how much it will actually cost you to get it up and running. Then figure an offer, keeping in mind it was free to him.
Unless it's your size exactly, and you plan on riding it for a while, I would say just let it pass on by.