I also think we should be able to save/export the favorites toolbar.
However, I never liked how the favorites function works because it is so disconnected from the brushes:
I can not change favorite brush settings
I can not see what brushes are added to favorites from the regular brush panel to find it
I can not turn off the fixed size, most of the time I don't want to save the size of the brush because I can not quickly switch between 2 brushes and paint seamlessly
For now, I completely replaced the favorites function by just putting my favorite brushes into a separate folder in the brush panel and use the next/previous brush shortcut to quickly switch between them to avoid any of the downsides of the favorites function. The only problem (not a big one though) with that workaround is that I can not keep it in a small panel on the screen or add a specific brush to the quick menu.
What lucky clan could do is basically the same, put the favorites automatically into a separate folder in the brush panel where they can be easily found, modified and exported. And when they also make it possible to add favorites without size, then I would not need a workaround anymore