Thinking about this some more, one potential problem would be how to handle the row based Color Coding. For example, if a user has a light grey row highlighting filter it would clash with the read-only field color.
I guess an easy solution would be that the column type highlighting supersedes row Color Coding, in which case the Color Coding is applied only to the input cells. A slightly more complicated solution is color mixing where the Color Coding is made one shade darker on calculated cells.
Another platform (Grist) tackles the input vs calculated columns differentiation problem with an icon prefix (example below), which works well but isn’t as clean from a design perspective IMO. I think most users understand that a grey form field (when others are white) indicates read-only.