On the position player side, I don't think there's a single position other than CF that we can look at and say, "nope, no upgrade needed at all, we're definitely all set for the future." What we have are over a dozen ifs that, if most of them hit, then maybe they might have an outside shot at contention next year. IF Lee can maintain his recent run, IF Keaschall's arm isn't permanently ruined and he can stick at 2B, IF prospects like Jenkins and Culpepper can come up and produce immediately without the usual setbacks, IF Outman and Roden aren't a couple of lemons, IF Lewis can put it all together for more than three weeks at a time, IF catching depth can materialize from somewhere, etc. etc.
And this is just the lineup. There's a whole lot of ifs needed to break your way to convert a pile of fringey starter prospects into a full rotation and bullpen in less than a season's time. Because that's what also needs to happen if they plan on contenting next year.
So who should be getting targeted in trade? Any bats (well, maybe not LH hitting corner outfielders) that could be contributing at the major league level by the end of 2026. If you're relying on ifs to get by, then you need as many ifs as you can get your hands on.
If they're not making painful 40-man decisions, then they don't have too many prospects. They are not making painful 40-man decisions at this time.