My Xiaomi Mi Band 4 lasts me 4 weeks with a full-color AMOLED display (without NFC). That's the base to compare to.
1,496 karma · joined February 22, 2007
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240x240 is ~56.25 kB at 8 bpp. the screen is RGB 65K colors, that is, 16 bpp; so the framebuffer size should be twice larger. I assume that the display controller has its own memory. True, you would need another 112,5 kB for double-buffering, but maybe you can do without it.
apt install lubuntu-desktopI am planning on doing a NAS to, but decide to forgo the low power aspect and use an older PC hardware. But not too old, apparently, as FreeNAS requires 64-bit and 8+ GB of RAM, nowadays, for the ZFS, apparently.