That's pretty wild! I read something recently where they were testing the possibility of making bullet proof vests with spider web. I recall something about one strand of web tensile was stronger and more flexible than an equivalent strand of steel...or something like that.
I'm obviously curious what a set of ukulele strings made this way would sound. Since we don't have a way to synthesize spider silk yet it's all rather silly, but interesting!
Not all that far-fetched. Guitar strings are still available with (caterpillar) silk as a core wrapping, and pure caterpillar silk strings are still made in China (though not for guitars or ukuleles).
Whether from a spider or caterpillar, they wouldn't be cheap, but if the demand were there, they should certainly be doable.