Starting over.
VS2022(without code)->vMicro->New Arduino project->GrblMega-2023_08_08.
Created in Documents\Arduino, however, not in Documents\Arduino\Library\ as GrblMega_2023_08_08 (note - changed to _).
VS2022->renamed solution from GrblMega_2023_08_08 to sln_GrblMega-2023_08_08, project from GrblMega_2023_08_08 to GrblMega-2023_08_08, GrblMega_2023_08_08.ino to GrblMega-2023_08_08.ino. Deleted .GrblMega_2023_08_08.vsarduino.h, left behind .GrblMega-2023_08_08.vsarduino.h.
Renamed Documents\Arduino\GrblMega-2023_08_08 folder to sln_GrblMega-2023_08_08, sub folder GrblMega_2023_08_08 to GrblMega-2023_08_08, changed sub folder GrblMega_2023_08_08 items to GrblMega-2023_08_08.
Edited sln_GrblMega-2023_08_08.sln-> changed GrblMega_2023_08_08 items to GrblMega-2023_08_08.
Documents\Arduino\sln_GrblMega-2023_08_08\GrblMega-2023_08_08-> __vm, bin, obj, src, GrblMega-2023_08_08.ino, GrblMega-2023_08_08.vcxproj, GrblMega-2023_08_08.vcxproj.filters.
Cut Documents\Arduino\sln_GrblMega-2023_08_08 folder, pasted to VisualStudio\GrblMega\
Using GrblMega-2023_08_08.vcxproj into VS2022.
Renamed solution from GrblMega-2023_08_08 to and saved .sln to VisualStudio\GrblMega\sln_GrblMega-2023_08_08 folder.
Using BC4, copied saved src files to this project src.
Right click the project-> click Add-> click Existing item-> selected src items.
Right click the project-> click Add-> click Existing item, navigated to src\GrblMega-2023_08_08 folder-> selected GrblMega-2023_08_03.ino.
Project now has header file, source files, and GrblMega-2023_08_03.ino.
vMicro build button is gray.
sln_GrblMega-2023_08_08 folder
sln_GrblMega-2023_08_08\sln_GrblMega-2023_08_08.sln
sln_GrblMega-2023_08_08\GrblMega-2023_08_08 folder
sln_GrblMega-2023_08_08\GrblMega-2023_08_08\GrblMega-2023_08_03.ino (missing-> copied from src\GrblMega-2023_08_08 folder)
sln_GrblMega-2023_08_08\GrblMega-2023_08_08\src\ .c, .h, .cpp, .hpp
.GrblMega-2023_08_08.vsarduino.h contains #include "..\GrblMega-2023_08_08.ino". I assume that is from the src directory.
Build button now available.
Confirmed the same errors as Arduino IDE:
error: initializer element is not constant item was declared as const.
error: unknown type name 'class'; in five(5) .hpp files of ten (10) .hpp files that declare a class.