FreePascal have one. TCL, before.
The bigger problem, I think, is the language tie-in. For get the amazing Delphi/FreePascal UI you need to work with pascal.
To get TCL-UI, you need to work with TCL. This mean anybody that not want to code on that not even consider the option.
And how integrate your language of choice? You need to pass by C. C sucks. SUCKS SUCKS SUCKS. Is so bad that is the glue for native development.
In the other hand, Elector/React Native is tied-in with JS. If C sucks, JS sucks even more, BUT, you DO NOT HAVE A CHOICE. Is Js or the highway by proxy of the browser. So, even if you code in other language, you MUST (not everyone, but enough) soon or later to accept this fate.
And interface with JS is not as bad as with C.