[deleted] I've had zero issues
That may well be. I also had zero issues installing all kinds of third party operating systems on numerous Nexus and Pixel devices over the years, and GrapheneOS installed nicely (via cli) on the Pixel 3a. So I guess it must me my bluejay device which behaves somehow strange.
treequell There are no such issues with web installer.
Of course not - that was what I saw using the cli installer, the flash-all.sh script stopped after flashing the first slot, so from there on (after rebooting the device) I tried those lines one by one myself, just with copy & paste from the script to the command line.
treequell If you're still struggling with your PC
I don't think that I'm stuggling with my PC. I'm retired by now, but before that I helped the Debian project a bit, was a system administrator in healthcare IT, and also with IBM for several years in technical support. I think I know my way around computers, except that I don't like Windows or Mac much (have been on Linux for over 20 years, also tried some BSDs and supported Solaris before that).
But no bad feelings, again I thank you all, and it's all good. For the moment I'll stay on stock Google Android (as do my wife and daughter anyway), and on the 3a Graphene was awesome, but DivestOS is also nice.
Thanks all.