Its even worse when you force Firefox to use wayland its icon doesn't even show.
Edit: Oh since everyone now is confused; I only have the flatpak version of Firefox installed yet it doesn't use the pinned icon and doesn't even use the firefox icon under wayland at all.
Microsoft Teams has a high contrast mode. Signal and Threema are both high contrast originally. That's all the electron apps I am consciously using.
And all of them natively support scaling up by pressing CTRL plus the + key.
They are actually much better in this regard than most native apps.