Breath focused meditation gear syncronized with pulse rate - today people breathe based on a count, like 4-7-8 is a popular pattern. 4 count inhale - 7 count hold - 8 count exhale. problem is the pattern doesnt account for metabolic level, so I plan to use pulse sensor to monitor pulse and breathing count will be in terms of pulses. This might create some feedback loop so not sure if it will work.

The gear I have is a cheap heartbeat/pulse monitor integrated with raspberry pi.