For me the key is WebMonetization, if it will partially replace the advertising on the Web there are more chances that casual users will stream microdonations to PeerTube content creators automatically while watching their videos.
Coil's implementation of WebMonetization already let its users support Twitch channels with microdonations. Imagine if at a certain point YouTube supports ad-free version of its videos if the user is streaming microdonations with WebMonetizarion. And most other premium Web services do the same, for example newspapers. At that point the WebMonetization userbase would be so huge that PeerTube instances can be supported by most of their visitors.
Anki, Calibre, MuseScore are examples of Qt apps from FlatHub not using Breeze, I'm not aware of any way to fix this and FlatHub maintainers just reply "we stuck to whatever upstream does".
Instead VLC is an example of Qt app from FlatHub that uses Breeze in Plasma.
Flatpak should have a way to detect the current session is Plasma, install KDE runtime or whatever is needed and makes all its Qt apps use whatever QtWidget theme the user set. Otherwise the Flatpak Qt apps (or at least FlatHub's in case we come up with a Flatpak repo optimized for Plasma) would always be second-class citizens.