From one newbie to another, welcome!
I’ve read about the invasive clock and just think it is Google being all controlling. Google is always right remember. They know everyone wants it, so you have to have it. I haven’t yet upgraded to 10 but that would have me trying other launchers too. Like you, I put up with the dead search bar. Does this clock show up on every page of the home screen?
You make a good point about notifications. There may well be something owners can switch on somewhere in the settings jungle? I’d be looking right now if I was on 10. Pleased you haven’t had any problems.
I agree with you that there could many reasons for the problems people are facing with the upgrade. Regarding your alarm clock issue, I did read here that someone had a scenario where the alarm wouldn’t function unless the phone screen was active? Every bug seems different. You must have switched off automatic time and date then. Makes sense if your ISP is porting you back. You will have to reset the time whenever you re-instate the battery now though!
True, no security or OS updates for FP3 users still on Android 9. Applications will still support upgrades for as long as they still support Android 9.