I agree with all of your points and I probably would never use this product. That being said regarding Linux support, given the fact that Fig effectively needs to hook into your terminal emulator and your shell to drive a custom overlay, it seems like it would be a huge headache to add support for Linux given how heterogeneous the terminal setups can be on the platform. Imagine having to support urxvt running zsh on X11 and the gnome terminal running bash on Wayland or xterm running tcsh or...

I think on Linux it would make more sense to directly modify one of the many existing terminal emulators to add this functionality or you'll have to severely limit the supported configurations.