A lot of this is work culture. You can push back by trying to formalize the research phase. Saying "I'm working on the architecture/design document, we have some known unknowns regarding [foo] I'm hammering out" shows other people in the meeting that you are working towards their problem in a meaningful and structured way.

Ultimately, if the people in the org want to push the work to xyz instead I would let them. Maybe xyz is as good as they think, but probably everyone in that room will enter a slog project/feature.

When someone makes a threat your default behavior shouldn't be to back down.