You may need to externalize the responsibility, to have someone else "make" the decision.

For myself I've found someone who is above me in our org, even though they aren't particularly technical. I can take them these problems, they'll hear me explain why I think X is a good direction, or why it's better than Y (even though I'm uncertain of the outcome). They will ask sensible questions (costs, risks etc) and approve the direction, eg "then I want you to pursue option X, and come back to me when you hit unexpected circumstances".

This person can be anyone that you feel some ultimate responsibility towards - in a one-person startup perhaps it's your significant other, as you owe it to them to be efficient and effective (and not wasting time procrastinating).