You may be interested in MatPlotLib for Python and maybe something like mpld3 to get it to the browser. I've been trying a few frameworks out recently, so I've seen a few Python options that use the browser as their main window. NiceGUI has a browser front end and graphing that may be able to do what you want as well, but there are others you can find. You might look for tutorials on YouTube if you're having trouble deciding, to see how difficult it is to learn and work with.
If you know any c++, there's a long but descriptive list of frameworks available on GitHub, sorted into categories, that could help narrow those options down.
It probably depends a lot on what you already know, but there are more options than JavaScript. You have a lot of good keywords to narrow down a search. GUI or graphing framework browser frontend open source (no license)
You may be interested in MatPlotLib for Python and maybe something like mpld3 to get it to the browser. I've been trying a few frameworks out recently, so I've seen a few Python options that use the browser as their main window. NiceGUI has a browser front end and graphing that may be able to do what you want as well, but there are others you can find. You might look for tutorials on YouTube if you're having trouble deciding, to see how difficult it is to learn and work with. If you know any c++, there's a long but descriptive list of frameworks available on GitHub, sorted into categories, that could help narrow those options down. It probably depends a lot on what you already know, but there are more options than JavaScript. You have a lot of good keywords to narrow down a search. GUI or graphing framework browser frontend open source (no license)