Do I believe it’s possible? Yes, but let me put it from my perspective first. Let’s say there is a cultural protestant who is at the evangelical church “every time the doors are open.” They have no depth in the faith aspect, only in the social. Now, they attend mass with a friend and are drawn into the beauty, liturgy, the catechism, etc… and truly have a conversion of heart to follow Christ. I can say, even from this side of the Tiber, they are better off there.
You’ve no doubt heard of cultural Catholics who are like the evangelical above; no depth in the faith. What is better? For them to stay in that, or for them to have a conversion of the heart? And what if that conversion could come about if they heard the word preached by a particular baptist preacher? Yes, I fully understand that Catholics would want them to have that depth as a Catholic in a Catholic congregation. Even supposing that Catholicism is the true path, could it not be within the realm of possibility that someone could need the Spirit to take them to a place they could hear a certain message? Even if that place were in a Baptist church?
Do I believe God wants us all in the same place? Absolutely. Do I believe God can use fellow Christians to push us farther in our journey despite our fractures? Yes.
As to your last part about teachings, I would disagree, but that’s a different conversation.