Here are two new Garmin device apps, hot off the compiler! 
Ruuvi Heat Index Data Field
Heat Index measures how difficult it is for your sweat to evaporate. Higher index = less cooling = higher heart rate. Internal Garmin temperature sensors often read incorrectly because they sit against your warm wrist, or in the case of cycle computers, are exposed to the sun - an external RuuviTag can remedy these conditions.
[Modern devices edition, Alternative devices edition]
Ruuvi 3-in-1 Data Field
This is a combined version of the prior Data Field apps, which all displayed and recorded individual metrics. This combined version is great for those who want all metrics, but use a Garmin device that only supports a small number of Connect IQ fields running simultaneously.