1st + Neighbours + Scandella is a good enough return for me to consider, to be honest.
I like Neighbours because I think his profile would be an interesting pairing with McTavish.
I don't see the Blues paying the equivalent of two firsts to turn Scandella into an unsigned Lindholm. The deal makes sense only if the Blues plan on extending him, so the Blues would want to talk to the agent for a comfort level or involve a conditional pick
in addition to a 2022 1st.
I also think they particularly like Neighbors enough that they would pay two firsts before they did a first + Neighbors. It's tempting to throw Scandella in return because of some help with cap but I think Armstrong won't want to subtract experienced NHL defensemen for a run. I think he would look for another way to make the cap work for this year, most likely involving having moved Tarasenko by then.
It could be 2022 1st + prospect (not Neighbors/Bolduc) + conditional pick
Edit: Before it gets misconstrued by my own side because I said it "makes sense," I would personally balk at the price of two firsts for a rental, and also I would balk at Neighbors or Bolduc being included. It's likely to be a competitive market for Lindholm if available.