I saw your video that is great. Please send us the instruction once you completed your test!I'm figuring it out how to fix the Dark mode with notifications after a week of testing some debloatings, don't need to remove vivo.pem. Tested with Messenger and it's working and showing perfectly on the lockscreen. I don't use whatsapp, so I couldn't test it, but I tested with other social apps, message apps, like instagram, tiktok, fb, signal, telegram and they are working same as in light mode. I will test more in the next few days then will give the instruction how to fix this if I'm not very busy.
Example video of Messenger working in Dark mode: