It's not just Linux that suffers from outdated tray APIs. It is the same on Windows. To create a status tray icon button, you need to call the Win32 Systray API (the oldest Windows subsystem, forget about using WinUI or UWP). The way apps like Google Drive and Dropbox do their fancier systray popups is that they get the x,y coordinates via the systray API (NOTIFYICONDATA passed to ShellNotifyIconA) and then render a chromeless window at the location with a slide up animation via something like Electron. I don't think the default systray menu can be styled to any reasonable extent.
One of the most difficult programming challenges I have encountered is calculating and displaying automatic drag and drop alignment guidelines/rulers (like those in Figma and PowerPoint that show up when you drag two element close to each other or near certain ratios) efficiently. They are not documented anywhere despite being a very common pattern. Most drag and drop libraries and framework don't have out of the box support for it as it requires deep low level integration.