Just create a Pygame REPL, which is among the Kivy dependencies, and install Kivy with the package manager or by adding
requirements.txt. Starting such a REPL in a new session takes a while to download and build the required libraries, at least several minutes. So be patient.
The attached REPL runs the Kivy Showcase, a demo app that showcases some of Kivy’s features.
It works fine except for a few overlapping widgets in the top bar. And it has some latency issues, but this poor performance is a consequence of the experimental state of GFX. If you adjust the handles along the frames of the panes of the REPL to close all the panes except the app’s, you can use most of the page area. Here’s a screenshot of what it looks like. I look forward to GFX supporting running apps at the full screen size in a separate page, like it’s now possible with text REPLs.
The work of @Saibot84 put me on the right track. He experimented with various ways of running Kivy on Repl.it, for example with Polygott and Python REPLs.
Polygott REPLs get stuck when downloading libraries. So I found that the simplest way of running Kivy is to use a Pygame REPL. Unlike @Saibot84’s Pygame REPLs, however, it’s not necessary to directly add the Kivy dependencies to