No one ever builds anything from scratch. You need to define what technologies/dependencies you are willing to accept to deliver your product to your customers. You should identify:
- What technologies you or your team are comfortable working with
- Costs involved in licencing these technologies
- Which suppliers can you source from (eg. if you are building a robot lawn mower, which company could supply the engine? Or will you build it in-house? Or will you make it electric instead?)
- How popular are your technology choices? If you need to hire staff, is it easy to find people with skills to work with that technology?
Your tech choices will introduce constraints to what you can deliver. Maybe you won't be able to support mobile devices, because the UI framework you decided on doesn't support responsive design. Think about what you will be delivering to a customer before making tech choices. Once you select your technology stack, it is difficult and/or expensive to change.