If we get a spin-off with Vel and Kleya it shouldn't take place after RotJ
I think all of us have seen Tony Gilroy's reaction to the idea of a Vel and Kleya spin-off about them as imperial hunters. And I think it gave a lot of Andor Fans Tunnel Vision regarding what a spin-off could be.
First of all, I believe dragging back Dedra would be a mistake and introduce a common Star Wars critique that Andor avoided: That the Galaxy feels small. She's a disgraced former officer, why would she be a priority after the war? Well, for fanservice. Of course it could work with the right writers. But her story ended in such a perfect way and I'd rather keep it that way.
Secondly, a common critique of RotJ is the fact that the second Death Star feels lazy. Because it is. ANH got similar critiques, but Andor and Rogue One has since filled that gap. So why not place a Vel and Kleya show between ESB and RotJ? A show focused on the rebellion licking it's wounds following Hoth and an espionage plot focusing on them trying to discover the full extent of the Death Star program. Throw in some bothans as well damnit.
Or leave the show as it is. As interesting as I find this concept I don't want it to turn into something mediocre following how great Andor was.