Some time ago I helped build a software that heavily used some python GIS libraries (GDAL, rasterio, etc) and we needed a UI for some windows users. We chose cefpython[1] to the job, as we could interface easily between the python and JS parts. The development experience is not so polished as of Electron though.

Nonetheless, is a great project and not so difficult to use, although not perfect, it worked perfectly for our needs.

[1] https://github.com/cztomczak/cefpython