If the first were true, I doubt Russia would be spending so much in the way of resources on simple territorial expansion (with the implicit long term expense of huge resources governing the conquered/occupied territory).

The invasion isn’t good ROI for them otherwise, even if it went well, which it does not appear to be.

I think the USSR restoration empire building narrative is overblown.

Also, if what you say about red lines were true, the US would not be so hesitant to provide lots of advanced aircraft to Ukraine, which they have not done as yet despite this clearly being a full enemy-of-my-enemy proxy war.

Signs point to everyone trying to avoid escalation.