Great tip. It does take some work for a single file though. I know more people have asked for this feature in the start menu before in the last 4 years. I've also frequently sent feedback on this matter.
Contrary to microsoft's intention I've used the start menu as the new desktop for the last 8 years. It is possible to pin office files as a live tile. Since the start menu offers the basic same functionality as the startmenu on windows phone, it is natural and expected to have this functionality in the startmenu. I have hardly to not used the windows desktop envrionment in the past 8 years. It is natural to use the start menu full screen just as well as the desktop enviroment, even on a desktop pc. For me the live tiles provide advanced functionality and glanceablility of information over the classic desktop environment. With the live tile folders and start menu sections it is also possible to manage files on the desktop. Unfortunately, despite extensive feedback early on in the windows insider program, being able to pin any filetype as a live tile is still not reality. At least not as easy a pinning an office file from an office app; or a pdf file or webtile from Microsoft Edge. But even with these 5 options, one would think the next step is not difficult to make as I would think the code is basically already there. But Microsoft has chosen to frame the value of the start menu differently as windows 8 start menu, tablet first frame, was a to big a change for the genernal consumer in the early days. Windows 10 has tried to pick up the pieces from there, and is still evolving to date. Though the tablet experience, and thus also the live tiles experience has been less in the picture, even though it is a valuable UI and tool to use today. I use it for personal and business use and it works great in my workflow.