If it does work fine without Google Play service, then there's not much you can do with this kind of pop up other than modifying the APK (or perhaps using some kind of hook framework like Xposed).
You could try something like microG, but your ROM would need to support signature spoofing.
It is nonsense to forbid the world’s people to eat just because one person has choked to death when eating; it is nonsense to put the world's boats in disuse just because someone has drowned while sailing; it is also nonsense to eliminate the world's military forces just because one sovereign has lost his state due to his military action
You can express that you are sick of their showcase of their lifestyle just as much as they can showcase them. However, saying that the entire subculture is nothing but shoving their lifestyle at everyone's face is neither cool nor is it largely the truth. Sure, maybe some of them are annoying, but that's not the basis to dismiss the entire subculture.
Kinda late by now, but I think this was because someone first machine-translated Abstract to Chinese, which typically means 抽象 (thus being the pick for the machine-translator program). This was then machine-translated (badly) again to English, causing the pumping elephant nonsense.
This is for file sharing, while Syncthing is for file synchronization. While you could use Syncthing for file sharing as well (and I have used it for that before), it's definitely more complicated to use, and requires a bit more setup.
Just FYI, Arch Linux has a tool called Archiso that you can use to create live ISO image. You can copy the default releng config and edit the package list accordingly.
If you are on Plasma 6, it should be "System Settings" - Keyboard - Advanced, select "Configure keyboard options", and you'll find the "Caps Lock behavior" - maybe even two, but one of them have a lot of options as to what you want to do with your Caps Lock key.
Xournal++ supports other architectures. They might not have compiled binaries for other architectures ready to be downloaded on their GitHub release, but it's packaged on at least postmarketOS (i.e. Alpine Linux) edge (I have it on my "Chromebook") and Debian Stable.
I have a Samsung Chromebook that also has ARM SoC, 4 GB of soldered RAM and eMMC storage. I installed postmarketOS on it, with desktop KDE Plasma 6, and with 4 GB of ZRAM, it is definitely usable - I could run Xournal++ without much problem. It's not butter smooth, the scrolling can be stuttery, but it should be enough for light notetaking. Granted, my SoC is older and weaker (RK3399), so your mileage may vary.
If you are using containers, it should be fairly trivial. Otherwise, there might be some renaming to do, but Forgejo should be 100% compatible with Gitea (at least right now). Just make sure you have a good backup in case anything would happen.
If it does work fine without Google Play service, then there's not much you can do with this kind of pop up other than modifying the APK (or perhaps using some kind of hook framework like Xposed).
You could try something like microG, but your ROM would need to support signature spoofing.