Having tried a couple of the SaaS boilerplate options or even better the SaaS-for-SaaS systems mentioned by other commenters, I found there to still be a lot of manual setup and work required. Questions and decisions like the OP's take time and energy away from innovation.
Makes me wonder if someone hasn't yet come up with a cloud based SaaS to streamline that. Something basic, ideally it would handle basic language/eco-system selection, automatic SaaSSaaS boilerplate service select, on-boarding and configuration and customization, ideally transparently federated over several vendors? Maybe a paid tier that uses CoPilot-like-AI and NoCode to come up with your idea and then execute it. SaaS4SaaS4SaaS. SaaSCubed?