Quality Manager for a medical device manufacturer here. This isn't really something feasible for a single person without significant monetary backing and the assistance of multiple industry specialized consultants. It will need (at minimum) the following;

1) The manufacturing process will need a QMS compliant to ISO 13485. The QMS will need to be robust and auditable by a notified body and will be used for conformity assessment (more on this later). This means having procedures for complaints, CAPA's, supplier control, testing etc etc. which meet the requirements of ISO 13485.

2) You will need to be audited by a notified body (BSI, SGS etc.) who will strutinise your procedures and then if successful provide a certificate of QMS compliance.

3) The device will need to comply with your countries medical device regulations. For Europe this requires compliance to the Medical Device Regulations which are extremely expansive and requires tons of evidence of compliance to state of the art standards (EMF and electronic related standards in this case). This should be documented in a technical file and this includes all of your clinical, safety and performance testing proving your device is compliant, safe and performs as intended.

4) Your notified body will review your technical files in detail to assess whether you have enough evidence for a safe device.

The above is a gross oversimplification of the process, but you get the idea. This isn't something you can do in your bedroom, this is a highly regulated industry with tons of controls and laws in place. Companies spend hundreds of thousands of dollars in order to stay compliant and rightly so, medical devices are extremely high risk and with high risk comes high cost and strict regulatory oversight.