I know I’m asking a stupider than stupid question cos of the volatility/write limitations of flash - but -
Is there anyway of storing sensor data on the node so that when it’s not connected to HA it still logs sensor data (even if it’s just on state change) and then “fills in the blanks” when HA is bk online (or has the ability to show on a display like LVGL)
For sure the answer is no, something this small cannot…
But then again I remember when esp32s/esphome did not have a web server or the ability to display on anything other than a LED…
Since you mention flash, then I guess you want it to go in deep sleep and that brings up the issue with a missing real time clock (RTC). Without a RTC you would not know when the data is collected and then you have no way of importing it to HA in the right place.
There are RTC available to ESP, but if they work with ESPHome is unknoen to me.
A RTC and PSRAM will mean the power usage will increase, so a battery powered sensor would need extra batteries to perform as before.