This uses Charles Weld's Tesseract wrapper (tesseract.dll). Although the wrapper includes support and tests for .NET Standard, I couldn't get it to work. The problems being System.Drawing.Bitmap and AppDomain.DefineDynamicAssembly. I used the Microsoft shims for those but eventually the wrapper uses the real objects/methods (via assembly ref) and at runtime netcore knows that (shim)System.Drawing.Bitmap != (real)System.Drawing.Bitmap and throws an error.
The upshot: it doesn't work in .net core... I tried really hard (for a day anyway) and then gave up, but it was fun being back in C++ land again :-). Feel free to try it yourself and let me know (I much prefer using core).
While the library works for both x86 and x64, x64 is much faster, so if you can set the calling assembly to X64.