I still use the UWP app on the Surface because of the unusable touch support of the Windows app. So, this question isn’t about “fixing” touch support, but rather making it useable as it currently does not exist - on either the web browser version of Plex or the desktop app.
Any response from a Plex exployee? Windows convertibles are definitely becoming a popular, just look at the moves by Microsoft. Most flagship laptops come with a touch screen option.
Really, many of these touch fixes would likely be simple changes on frontend code.