I'm a painter who develops reference images from my photos and then paints from the reference image displayed on my monitor. In PS I superimpose a grid on my reference image and draw the same grid to scale on my canvas. Generally my image dimensions don't allow a grid with the segment size I want to fit exactly on the reference image (or canvas), so I wind up with a row of partial grid segments along one vertical +/or horizontal edge.
That's generally not a concern, but in the case of the image I'm working with now the grid I've made and wish to use would align much better with the image elements if I could rotate it 180 degrees, My PS/ computer tech. ability is low. I've seen references to "Guides" which can be rotated. I'd rather not get into that. Doing something like a screenshot with the grid imposed and rotating wouldn't work because of image quality loss, and the loss of being able to zoom in and out using the reference image's pretty large pixel dimensions to their fullest. I'm fine with creating my grids in PS - size, color, subdivisions etc. but cannot see a way to rotate the grid independently of the image it overlays, nor could I find any answers about how to do that online. Any help will be much appreciate I