I am not a developer, just thinking out loud.
Fedora Workstation has the codec problem mostly solved now that OpenH264 is easlily installable. I think that alone fixed a lot of issues. For everything else there is rpmfusion/flathub.
On silverblue things are more difficult - the base image cannot contain openh264 due to licensing and adding other codecs to the base gstreamer is probably not a good idea as it will require overlayed packages.
Now that SIlverblue installs flatpaks by default, would it be possible for there to be an org.gstreamer* flatpak installed which can be extended by flatpak extensions, which is called by a gstreamer shim in the default install?
Is that possible now by aliasing the gstreamer command?