Context is important here. Startups are in a totally different situation from an operating manufacturer. If you aren't releasing a product for use, a full quality management is really just for practice (not a bad thing, but not yet returning much value).
If you are at an extremely early prototype stage, I would say implementing a full QMS is a waste of your time and money. Focus on your product's operating principles and market viability so that you can secure the investment you need to keep running. Full quality management is indispensable, but it needs to come at the right time if you aren't pulling profits. Perfecting your document control processes is pointless if you don't have a device that actually works and makes sense.
For a lot of medical devices, it's probably appropriate to just look at the scope of quality management you need to implement to achieve your next milestones - for example, in the US, an investigational device is exempt from many requirements other than basic design controls. You could implement many other practices that are beneficial, but in that situation I wouldn't be forking out a ton of money to get a full QMS certified just yet.
For this reason, and many more, we would need a lot more information about your situation to understand what is really required for your device and what the best practices would be.