1. Update OTA does not find this new build.
2. Flashing this build over the last lineage-18.1-20201219-UNOFFICIAL-amami ended in a boot loop (at Lineage animated boot). I repeated this 3 times.
Then I made a factory reset.
3. I miss "long pressing backspace stops the running app".
4. In Trust I see SELinux deactivated.
5. and in Play Store/settings: device is not certified.
6 You wrote " you'd have to add a androidboot.selinux=permissive to the kernel command-line".
Sorry I don't know where :-(