This is probably a silly question but how do you think open source development works and what is adequate compensation?
Did a search for ubuntu "integrity: problem loading x.509 certificate" and the first result indicates out of date bios certificates needed for secure boot on older laptops. Disabling secure boot seems to be the suggested fix.
It's doesn't have anywhere near the same feature set or polish but I think neolauncher probably comes the closest to replacing nova as far as open source solutions go.
There are too many variables that go into battery usage to get any meaningful insight. Different apps, cpus, screen brightness/refresh rates, active radios, etc... It's an endless list. Best you can do is compare with someone you know with the same model who has similar usage patterns. Good luck.
If you're going to store something on someone else's computer (Google cloud), they have every right to control what is and is not allowed on their systems. Don't like it? Use encryption, selfhost, etc...
I know these guys are too busy to do it but I would gladly pay a monthly fee for a podcast with Steve (GN), Steve (HUB), Wendell (L1) and Gordon (PCWorld).
https://github.com/erkserkserks/openboard
That's the fork with swiping.
It looks like that instance isn't using the most up-to-date version since the "press go" issue has been fixed. Try to keep in mind that the initial commit was on June 24 and it's still very early in the development stage. If you look at the commits, you can see the developer has been very active.
Wouldn't getting something like a Kobo and syncing with Calibre be a much easier/cheaper option?