I never tuned to D. These days a number of tenor ukulele players are tuning tenors down to B or Bb.
I might have a starting point for you, but unfortunately don't have an ending point.
There was a gentleman named Dirk Wormhoudt that was very much a string, and instrument, expert. He operated Southcoast Strings. Sadly Dirk got ill and passed away. But here is a starting point for your search.
https://forum.ukuleleunderground.co...-tuned-to-adf-b-string-recommendation.102791/
At some point in time, there was an effort to get Dirk's sourcing information so that the people who relied on Southcoast for strings could continue to get them.
It is probably safe to say that ukulele strings, at least fluorocarbon, are in fact fishing leader. It is not safe to say that all ukulele strings come from the same source since there are numerous manufacturers. The source is always the key.
I have seen Oasis advertise their Baritone strings as Southcoast. That doesn't mean they offer a LL-NW set. I "think" LL-NW stands for Linear Light-Nonwound. Also, a wound C string might work for a wound B.
I never recommend just buying a bunch of fishing line as the cost is so prohibitive, sometimes to the point of being able to buy another ukulele. Many times a lot of it will be of no use, especially if you don't have a number of ukuleles to string. If you can find someone who sells packaged ukulele string sets you like, that is the best way to go.
Hopefully, someone here can direct you to a supplier that can provide a packaged set that will work.
Good luck.
John