So when she concluded her explanation I had to go "sorry, what I actually meant to ask was ...".
The interruptions for clarification and false assumption are not the interruptions OP is talking about. In the example given, person B does not try to actively take control of the conversation, just quickly inserts a correction and allows person A to continue. So there's no need for persona A to say "let me finish my thought".
It's not that women should be made to feel more comfortable giving these soft types of interruptions... it isn't that hard to correct someone's factual mistakes. It's that interruptions are used by dominant people as a political tool to assert hierarchies and for control. Women do it too, it's not a gender issue but I can imagine it more difficult in gender imbalanced teams and with gender stereotypes in play.
In my opinion if a person has to say "can you let me finish my thought" the interruption is never justified. Even if someone is rambling or mistaken, there are better ways to deal with that - for instance, asking them to be more concise in their presentation of their point. Being proud of a culture of interruption is admitting politics is how you make your decisions and how your team works together.
Person A: "If the system's going to be configured with option X-"
Person B: "We just heard we're definitely going with option Y"
Person A: "Oh thanks, so.."
Nobody is served by person A going on that tangent with a false assumption, so a quick interruption is fine.
Of course needless or rude interruptions are bad. Maybe part of this should be that women should be made to feel more comfortable giving necessary interruptions like in my example.