@Riley_S Thank you for seeking the possibility of this functionality in the future, if the dev team accepts the request.

Thank you also for enlightening me that the data is stored at each device. I have seen on GitHub that the device would respond to REST API. I will explore automatically downloading the data in a regular interval before the memory space runs out. Your response opened a door of hope that I can deal with this limitation. Manually initiating the data download from the phone app is prone to exceeding the 7-day limit.

A 32-bit data structure could be employed to store usage data for each 1-hour period. If we allocate 16 bits to the usage data, we can represent every value from 0.0 Wh to 3,276.8 Wh. With the remaining 16 bits we can represent every unique 1-hour period for the past 7 years and ~6 months. Thus, each usage record only need take 4 bytes of storage. Using only 262 kb we can store over 7 years worth of hourly usage data.

To make a concrete example, a usage of 1,987.2 Watt-hours during the noon hour of September 7, 2021, could be encoded as hexadecimal 79244DA0. The first 2 bytes store the number of hours back from the current hour [$hex(7924) = $dec(31,012) hours], and the second 2-bytes encode the Watt-hours x 10 [$hex(4DA0) = $dec(19872) = 1987.2 Watt-hours].