Unless your startup is building some new tech product (like a new database technology, or a crypto/blockchain system) that is going to be sold to customers, software code quality doesn't matter much, at least initially for sure, and may be ever too.
Most likely you are startup building a software application service that is augmenting or automating or orchestrating some real-world interaction (like an e-commerce shopping or supply chain systems), then you care most about getting your product market fit figured out.
What this means is testing your understanding of the potential customer's needs, selling your product value to those customers (switching them from their existing way of life to your way of life), figuring out the business model (what costs are you optimizing, how much it costs you to run it your way, who will pay for it, can you cross-subsidize something, how does your business scale, at what scale your business becomes viable, at what point do you make profits etc).
This usually requires a lot of experimentation and product iteration. For this, you need to have very high feature developer productivity with very low costs for getting experiments wrong. For the past half decade, this is achieved by not building any IaaS/PaaS stuff in house and using stuff from some public cloud platforms.
Today, a new movement is happening – it is #lesscode or #nocode movement – you use frameworks and rapid application development tools that allow you to write very little or no code to create your applications and iterate quickly with very low software engineering skills. This allows a startup to go very far with very little burn while hunting for product-market fit.
Once you know you have a good product that is on the cusp of scaling, you can revisit your choices and figure out how to optimise costs through in-house software development. The bar is raising every year for what makes sense to build in-house.