I recall knowing LPDDR consumes less energy, recently I've read more details: https://www.powersystemsdesign.com/articles/performance-vs-power-in-off-chip-ddr-sdram/22/5893:
Deep power down: Mobile products can also take advantage of the deep-power-down command in low-power SDRAMs. Designers use deep power down when the SDRAM does not need to retain its contents and when the system can handle a longer than normal activation cycle. In deep power down mode, the LPDDR SDRAM can disconnect all internal power from within the memory and will consume the least amount of power as compared to all other modes.
I was not able to find via web search about Linux support. I have not found info on it in Kernel page on sleep. AFAIK as Linux is used for Android devices, I expect it to support it. Does Linux running on Android support putting part of DRAM in non-refreshing state? Does laptop/desktop Linux (e.g. Ubuntu) support that ("knowing" which part of memory had not been used at all or if used, have criteria to decide which can be lost and use Deep power down during suspend)?