You are projecting. Personally speaking, I would choose Electron waaaay before I'd choose GTK. That probably wasn't an option for his optimized terminal, but would be Good Enough™ for just about anything else.
Electron is bringing an entire web browser in to provide a cross-platform user interface. GTK has become almost a web browser to provide a cross-platform user interface. That is why I started off with
Their CSS implementation is broader than what most actual browsers had 10 years ago. I would not have commented if I weren't already painfully familiar.
GTK has gotten so fat that it's more like a 2nd-rate Electron. Not that Electron would have done Ghostty any good...
I have a bad feeling that the only decent & consistent UI option under Linux is to target Win32 API, then run it under Wine.