May as well just run a PHP with Javascript on a personal web server with XAMPP. Even better, just create JavaScript programs and run them on a private web server so they work offline. Serving from a VM sandbox so the rest of your computer is safe. Each app can just be given a new MySQL database to store the data so they don’t corrupt each other. If you want more compute capability then you can upgrade to the online extension.
Better still write everything in C or C++.
Ha ha ha ha! … Obviously the VM would be Linux.
Don’t get me wrong I love C# and WinForms but it’s a bit narrow.