

Learning Linux can be difficult man. Even after using Linux as my daily driver for a couple years, I still feel like I know nothing man.
Real talk, start with dead simple stuff and go from there. Install a package from a package manager, update your system, make a file with terminal.
You dont have to be a wizzard man, docker shit is still over my head.

I could be wrong but no remote refs refers to not finding a repo for what you are trying to install, so either the flathub repo isnt added which it sounds like it is, or the app you want isnt in that repo.
So you may need to add the repo for that app: https://fcitx-im.org/wiki/Install_Fcitx_5