If they were planning on using their prospect pool to acquire relievers in trade, they wouldn't have dealt the entire bullpen in the first place - especially not Varland. They're not going to turn around and make the same trades in reverse just a couple months later.
If you want to realistic plan for rebuilding the bullpen, I think you have to limit it to internal development and free agents. I'm on record what I think about the viability of this plan, but I'll play along here.
First, the rotation needs to be sorted out, since the excess from that process will be your internal bullpen options. Lopez/Ryan (they're not keeping both, so let's split the difference and say they keep one and the other brings back some hitting), Ober, Matthews, SWR, Bradley are the leaders in the clubhouse for the opening day rotation.
From there, you need to identify who of your excess starters you want to keep developing as such to be the next men up from St Paul, and who maybe profiles better as a reliever. Abel and Rojas to me are locks to at least continue to be developed as starters - probably Culpepper too - while I think some of the guys with arm talent but injury issues should be sent to reliever bootcamp immediately. There, I'm thinking Prielipp and Festa. Even if they still have starter potential, if the goal is to be competitive next year, then you can't just wait on the rotation sorting itself out. Some have to go to the pen straight away. And putting the injury risks in the bullpen just seems like a smart way to play the odds. Hopefully in short bursts their stuff plays up to something approximating closer/primary setup man results.
And you're going to need to find some relievers of that caliber from your starter prospects right away, because you're not finding that in the current bullpen options. Sands and Funderburk (if you're relying on Topa, you're not competitive) may very well be able to fill bullpen roles, but not to be one of your top 3 high-leverage shutdown relievers.
So we now have 4 relievers in Sands, Funderburk, Prielipp, and Festa. That leaves 4 spots that need to be filled either from free agency or whomever is left behind in the starter development race. If you get a couple free agents, at least one has to be of the closer/primary setup variety - and historically the results of that are mixed at best. Internally, that leaves guys like Raya, Morris, Adams, Ohl, and who else - is Canterino still alive? - that you're hoping can swiftly transition from starter development to being an effective piece of the bullpen.
And that's why building a competitive bullpen for next year is really a tough needle to thread - you have to identify the guys you want to transition from starter AND they have to become effective in their new role in a short time frame. You can't wait until June to identify them as you might already be out of contention by then, and it's a pretty tall ask to expect multiple prospects to go from starter to effective reliever immediately. Even the recent success stories like Duran, Jax, and Varland didn't make the switch overnight. It will probably take some time.
Anyway, that's my best shot at a realistic (again, I don't think keeping all the starters and dealing prospects for relievers is realistic) bullpen for 2026