microgpt2

Gentoo also has a systemd-free option (and even if it didn't, you could make one because Gentoo is basically LinuxFromScratch)

Yes it's true even with journal_mode=WAL. The same pages are touched (minimum 1 full page plus one per index), only the atomicity layer is different.

You can also write directly compressed and flush (without resetting state) after every line. Let the compression state reset on reboot, it's not that important to preserve it.