Can I plant peonies on a steep slope?

[Linguaphile]

Just that, really. I have a steep hill in our garden and wondered if I might be able to put a peony there, or if the flowers will all just flop over down the hill from gravity. 🤔

Alternatively, how far away could I plant if it were near a tree? I have a flat place about 4 feet away from a cherry tree (it would get full sun still) and wondered if that would be a better place, or if it would be too close?

I think you probably could but you might have to be prepared to stake/support them if they need it. The main thing with peonies is full sun and not to plant too deep or they'll never flower. Someone else might have actual experience of this but I think its worth a go. They're possibly my favourite flower (just planted three) so I don't blame you for wanting some!
Alternatively could you make 'terraces' or beds in your slope ??

Yes the flat area near-ish to the cherry tree is actually a terrace! It would be about 4-5 feet away and the orientation is such that the sun makes the tree cast its shadow in the opposite direction, so I think it would still get ample sun there.

Lovely. It might be less hassle than the sloping bit. Good luck, hope you get lots of luscious blooms!