I Dont know if this will be of interest or useful to you ? But i have been using the sensors detailed in this project for over 18 months now and am just now needing to change batteries.. https://github.com/ThomDietrich/miflora-mqtt-daemon
(querying cira every 30 minutes 24/7..)
a practical broadcast range of 5m perhaps more without obstruction, i am listening through a wall..
perhaps hide under a jamjar to protect against rain, all mine are used indoors.. though that mau have an impact on the temperature they read?
And then perhaps you can move the pi somewhere more comfortable??
In use 10 sensors in the same pot will give 10 different readings within 10-20% of each other So you need to 'calibrate/test' each sensor to determine what it reads when soil is saturated, and again what it reads when the soil is dry.
and use that to bodge a display in % if needed, the sensors do read consistently , But maintaining consistent insertions into solid soil also helps. a sensor loose in the soil will read more 'air'.
also dont be tempted to use the xiaomi phone app as it could update the sensor firmware rendering it useless with this crack.
and after 18 months in the soil the pcb prongs for the capacitive and ec sensors are mucky on the face which simply wipes off and show no sign of moisture ingress at the edge at all..