I don't think the seriously considered playing Devers at 1B, except in private meetings and discussions. The "assurance" Bloom gave to Devers about playing 3B may have been a big part of never asking him. (I am assuming they never did.)
The Bregman signing and a new GM changed the dynamic, and that was not very long ago on the Bregman addition. The shoulder injury to devers and failure to trade Casas probably made asking him a low priority. Maybe it was brought up when Devers was talking about not wanting to DH. Probably not.
If I was the GM, I'd have at least asked about the idea, and if he didn't like it, I would not push it.
I think Casas will start hitting, soon, but I have no faith in his defense ever improving. The bar is set so low for Devers to match or exceed, I find it hard imagining him being worse than Casas at 1B. Hie quickness and range at 3B were not really the main issue: it was his erratic arm.