not it is not possible to use Visual Studio 2023 under WCE/WEC. I answered already your distrubutor, see following quotation: "it is not possible to use every Visual Studio (VS) Version with every WCE/WEC Version. In general following is possible:
- WCE6 with CF3.0 is supported by VS2005 only.
- WCE6/WEC7 with CF3.5 is supported by VS2008 only (at least pro version).
- WEC2013 with CF3.9 is supported by VS2012/2013/2015 (at least pro version) plus installation of Application Builder for Windows Embedded Compact 2013.
It may be possible to convert your old project to new (above refered) VS by open the project file with it (not solution file). But as the new platform is not in the project as “hack” is required before and you must add the new platform by hand (using a text editor).
It may be easier to create a new solution/project and add your old files and old settings afterwards."
You can access older VS versions by purchase a "Visual Studio Subscription".
Note WEC2013 is EOL in 2028!
So best way to stay on Windows OS would be to choose a newer platform which supports Windows 10 IOT (e.g. PicoCOREx).