Combining different UIs into one system (with possible switching between them) while most likely using webtechnology/python

first of all i am not sure if I am correct here with this question. Anyway, in the project I will be working on I should offer the possibility for "unifying" some already existing UIs so a user should be able to switch between them (maybe my using gestures or menus etc). Currently those UIs are implemented using different technologies, so e.g. one is webbased, one is done with GTK. *

So the goal is to find one shared base for them.

As a webbased UI is independant from the OS, I thought about making my solution webbased however I don't know much about the UIs yet. In general, they are very different regarding not only implementation but also design and complexity. One of the infos I have is, that it would be great if UIs can be developed using Python 2 as it is still mostly used by the developers of one of the UIs. So they are open to leaving old technology behind if I have a good recommendation that works for everyone and isn't too much hassle to switch to.

As I am still a beginner, I am struggling with what technologies to use.

It seems like anything webbased uses javascript and the frameworks I found for making python GUIs seem more outdated and less flexible compared to web technologies. Also I did not find out much about if a program can be integrated into a website or something like that. For most of them i don't know how relevant they are for my problem. So I would be glad to get some tips on what I could/should be using or where I should start searching.

Things I already found when searching are listed beneath.

• electron which is also sometimes mentioned together with Python like here

• django which seems to be for fullstack python web development if I am right

• i know that the already webbased UI uses flask and vue.js; also I already used react.js for a small project if that could be helpful

• this is one example where somebody starts programs via a web page (but I don't feel something like this would be a good fit, as switching between the UIs would probably not seem to be very fluid/consistent for the user.)

• kivy was something I found for developing python GUIs (it also seems to be able to use multitouch which could be interesting)

• as I said earlier one of the UIs is implemented via GTK so I found this similar question online

Thanks in advance. :)