I've been noticing a somewhat similar boom of new good-looking apps in the GTK/Gnome world. Although those are mostly smaller projects (single developer free-time pet-projects) with very small scope (doing one very small thing well), but the sheer number of those good new projects is amazing compared to the status quo of a decade or so ago.
And although you credited the MacOS specific applications boom entirely to the good toolkit, I think the GTK/Gnome app resurgence comes from a synergy of three factors:
1. The rise of more ergonomic programing languages (Rust, Go, ...) that make desktop app development more fun (GTK programing in C works, but it is like pulling teeth, soo much boilerplate).
2. The rise of new app distribution channels on Linux (e.g. Flathub)
3. And the improvements to the toolkit.