This is no where near finished but here's some first bits of startup notifications in #phosh (i'm usually using #epiphany on the #librem5 but I needed something that takes longer to start up so i went for #firefox):
@agx@agx Splash screens aren't very useful as they don't communicate anything to the user other than "something happened". We realized this is bad UX in web design decades ago. If it can't be instant, tell the user how long it will take. #ux#uxdesign
@zbrown Anything is better than nothing (which is how it is now). Communicating how long something will take can be done by plain text, a progress bar animation, or progressive loading. Even if the splash screen says "Loading" in plain text, that communicates more of what's going on to the user than a static app icon or throbber does.