If you're finding that your Deal Amount property isn't calculating the Amount you want to associate with the deal, you can now go to your settings to make sure the default Amount property displays what you and your Sales team want to see.
You can choose from Annual Recurring Revenue, Total Contract Value, Monthly Recurring Revenue and more so that you and your team can report on the values that matters most to you!
It's currently not possible to set the deal default amount per pipeline. I can see how that would be a handy feature though!
I would highly recommend you to submit this product suggestion to our ideas forum.
Our product team, who monitors the forum regularly, can read your specific use case and understand why this would be a useful functionality or change. It also helps other customers facing the same issue to advocate for its implementation on your behalf by upvoting on the thread as well.