Downgrading to latest android 11 based stock firmware (2021 october) was needed to install /e/OS “r”
Since /e/OS “s” (android 12.x based) has been released, now there is no more need to downgrade from stock android 12.
you wrote: “downdating to 2022 october 's android 12 based stock firmware could be needed to install e-1.7-s”
But the latest stock Android 12 for bramble that I found is from 2022 July. Since August 2022 there are only Android 13 stock images for bramble.
If I want to install /e/OS “S”, not “R”, would I need to install the latest stock Android 12 from July, and then e-1.7-s, or should I better try e-1.6-s?
Finally I got e-17-s-20230110… running on my bramble device.
But this was not easy to achieve since neither e-16-s-recovery nor e-17-s-recovery will boot, even if the latest stock Android 12 (SQ3A) from July 2022 was installed previously.
So I downgraded to the latest stock Android 11 from October 2021, RQ3A.
Then I installed e-17-r-recovery. This recovery worked.
Only with this e-R-recovery (e-S-recovery, installed by fastboot, won’t boot) I was able to install e-17-s via sideload. (There was a warning though, that this is a downgrade that could fail. Since in reality it wasn’t a downgrade but an upgrade, I overruled this warning.)
I’ll try the whole procedure again to verify this.
An unlocked boot-loader is the normal state of any android phone with a custom ROM, no need to worry about it. Google just sprays that message because they know you are trying to run another ROM on your phone.