Giving a PM’s perspective, the 0-1 journey requires you to be okay with vagueness & requires a lot of non data backed decisions at the start.
It also requires you to be effective at constraint based problem solving. Since resources are amiss, you’ll have to prioritise delivery over quality.
Another thing is that you have a bunch of smart people to interact with daily at your company. In a startup, it’s only you with your problems. No one to discuss, refine ideas. This personally caused me a lot of anxiety.
Good luck dude. Better to burn out than fade away. KC.