Last commit is two years ago. I'd recommend checking what you have installed. A quick search on GPlay finds what appears to be a clone that may or may not leak user data.
OpenBoard is no longer maintained. Heliboard is a good alternative.
I think Google Play on Graphene is a good compromise, since at least it does not have root access. Unfortunately it is very crippling to completely avoid Google on Android.
That being said, I heard others are using work profiles to isolate all apps using Google Play from their more private apps. I'm not doing that, but work profiles are nice for ... well work apps.
A fuel cell does not mean it's an ICE. It will still use an electric motor and probably even a small battery.
Hydrogen ICE exist, but are more complex and less efficient.
You could use Hydrogen to produce so-called e-fuels (we had a huge debate about them in Germany), but those can typically be used in normal ICE vehicels.
The option to use TOTP is already well hidden. It's not like someone who does not know what he is looking for and uses an Authenticator already will accidentally select it.
I mean, other file sync apps upload everything to a third party while you're working with the device.Then, when you use another device the first one can be turned off.
I'll add another condescending advice for you: Don't feed the troll.
No seriously, those two other commenters are either insane or trolling. They are completely ignoring your objective and just going on about "rejuvenation".
Please stay as you are and stand your well informed ground!
Even central currencies can work if you can make offline and peer to peer payments.
Not easy to pull off cryptographically, though.