Some nice examples can also be found here:
https://1stwebdesigner.com/9-free-open-source-flipping-clocks-using-css-javascript/amp/
Most do involve some simple JavaScript work. A good use case for a simple widget I think.
You could purchase a 7 Segment font, add that into your application, and use CSS to set the this font to be used where necessary.
Here is a link to font that will probably do what you need – https://www.dafont.com/seven-segment.font
Hope this helps