Coincidentally, I saw such a sloping ceiling recently in a new home finished basement. Because there was no reason for this in a new build, it looked completely amateurish. I'd be inclined to level the ceiling.

We are working on a renovation and adding a slightly vaulted/sloped ceiling in our entry and dining space. I’m having a hard time finding lighting that explicitly states that it can be hung on a sloped ceiling that I like! Then I found sloped ceiling adapters to add to lighting - any insight or ideas on this? Or insights about flush mounts or chandeliers on sloped ceilings? TIA!

Bev is right -- rods require special treatment for alteration. Even if you can cut one end of one section and not have to deal with threading, you need a clean cut or you will have a mangled rod and/or a messed up finish. The chains will be much easier. You installer should be able to shorten one side on almost any chain. If the available info doesn't tell you that it can be adjusted, contact the manufacturer or have the seller investigate it for you.

where you have your fan seems about right. don't know what style you want in there, but here are some options Make sure the canopy is adapted for a sloped ceiling https://www.lampsplus.com/sfp/63K14