If you know where the windows are from you might be able to simply purchase snap-in grilles from the manufacturer

Here's a source that says they can provide grilles for any window.

https://www.bigbluewindow.com/?gclid=Cj0KCQjw1ZeUBhDyARIsAOzAqQJnE1GOW6Kw5Qva_rnGTbWQ3khvXfbwj-YjQc3n3mCBeRzxmwiyvBIaAov_EALw_wcB

Interior? Exterior? Both?

I would love both especially for the doors

Lovely house!

Should not be a problem with doors. Where it can't be done easily if at all is with slide by windows (sliders and hung) as the clearance at the vertical and horizontal rails won't allow for the grilles and the operation of the window/door.

Here is a company that I have had good luck with: Creative Millwork | Engineered Grille Solutions for Windows and Doors

I built my own and adhered the to the exterior of the window

There is nothing about the fact that you have grids between the glass that would prevent you from adding SDL's (surface mounted). In fact, most factory SDL's have GBG's as well for aesthetics. Obviously you can't change the pattern and you'd need some precise measurements so everything lines up, but its doable.

Eastbay is spot on regarding the depth issue though, you'll need to check on that clearance to see what if anything will work. Some window lines don't offer factory SDL's becasue there simply is not enough clearance.