1) Some of the developments that could happen if every current smartphone camera could accurately detect breathing and heart rates are

Personal health monitoring: People could use their smartphones to track their vital signs on a regular basis, which could help them to identify potential health problems early on. This could lead to earlier interventions and better health outcomes.

Remote patient monitoring: Healthcare providers could use smartphone cameras to remotely monitor the vital signs of patients who are at home or in other settings. This could help to improve the quality of care for patients who are unable to travel to a doctor’s office or hospital.

Sports performance: Athletes could use smartphone cameras to track their heart rate and breathing rate during training and competition. This information could help them to optimize their training regimens and improve their performance.

Public health surveillance: Governments and public health agencies could use smartphone cameras to track the spread of diseases. This could help to identify outbreaks early on and take steps to contain them.

Some smartphone gadgets that I would like to see are
A portable glucose monitor that can be connected to a smartphone. This would allow people with diabetes to easily track their blood sugar levels throughout the day, without having to carry around a bulky glucometer. This could help people with diabetes to better manage their condition and reduce the risk of complications.

A smartphone-based stethoscope. This would allow doctors and nurses to listen to heart and lung sounds without having to carry around a traditional stethoscope. This could make it easier for healthcare professionals to diagnose and treat patients, especially in remote or rural areas.

A smartphone-based microscope. This would allow people to magnify objects and see details that would be invisible to the naked eye. This could be used for a variety of purposes, such as scientific research, education, and even home repairs.

A smartphone-based translator. This would allow people to translate text and speech between different languages in real time. This could be a valuable tool for travelers, business people, and students.

This smartphone HR and RR rate measurement will be useful for personal health monitoring in general. I am working around tourist spots and have seen tourists seeking medical devices during travelling such as bp measuring machine. Smartphone vital sign measurement would suit travelers so that they don’t have to buy one for the short term use.
Apart from human, I am thinking of using this kind of technology in animal and pet health. Because the pet couldn’t talk, some of the owner would probably love to know and take care of their pet health status. Moreover, without intrusive methods, it could be used to measure the observation of animals in national parks as well.

If the smartphone camera can accurately detect breathing and heart rates, those rates can be used as supplementary biometric markers for enhancing smartphone security.

If this is so, the smartphones might need to be equipped with specialized sensors or gadgets to accurately measure these physiological parameters, such as pulse oximeter sensor, respiration rate sensor, and machine learning algorithm to process and analyse the data from the sensors that could differentiate between the user’s normal physiological patterns and potential anomalies.