there's an app called Sober on flathub, developed by creators of Vinegar. i use it to play roblox and i can say it works without any issues. the setup is really simple, since it dowloads everything by itself
you should try papers. it's a new app that'll replace evince as the default document viewer for gnome in a future version. it's still in development but i've been using it for a long time and it's really good.
This is supposed to be the most used operating system, recommended for its ease of use. Meanwhile you have to sign in to use a clock app. Such a shame, especially because the focus timers are actually useful.
every chat app might use ~1GB because most of them are electron apps, which all spawn their own instance of chromium