I don't get why all startups don't just start with a PaaS like Render, Fly.io or Heroku. Why spend time setting up your own infra and potentially have to hire dedicated staff to manage it when you can do away with all that and get on with trying to move your business forward?
If and when you start experiencing scaling problems (great!), that's the time to think about migrating to setting up infra.
Because like every service-oriented offering, each platform differentiates as hard as it can to lock you in to their way of doing things.
Things largely look the same on the surface; this takes the most effect at the implementation-detail level, where adjusting and countercorrecting down the track is fiddly and uses an adrenally-draining level of attention span - right when you're at the point where you're scaling and you no longer have the time to deal with implementation detail level stuff.
You're on <platform> and you're doing things their way and pivoting the architecture will only be prioritised if the alternative would be bankruptcy.
If and when you start experiencing scaling problems (great!), that's the time to think about migrating to setting up infra.