I’m looking for a shader or overlay that could be used as a crosshair or aimdot.
All it would have to do would be to display png file of user choosing in the user selected portion of the screen.
I’m looking for it mainly for the PS1 Medal of Honor series which supports full analog controls but does not draw any crosshair without standing in place and holding a button.
Well, it turns out, that after 4h of searching how to do it I had an epiphany and made exactly what I needed. 
I have created windowed and fullscreen overlay that gives the ability to enable/disable a crosshair made specifically for PS1 Medal of Honor.
Here is the overlays cfg:
overlays = 3
overlay0_overlay = img0.png
overlay0_full_screen = true
overlay0_name = crshr_off
overlay0_descs = 0
overlay1_overlay = img1.png
overlay1_full_screen = true
overlay1_name = crshr_wndw
overlay1_descs = 0
overlay2_overlay = img2.png
overlay2_full_screen = true
overlay2_name = crshr_fscr
overlay2_descs = 0
By assigning a button for overlay change (Settings > Input > Hotkey Binds > Overlay next) I can switch between crosshair png image files that I’ve made.
img0 - crosshair disabled, it is an empty png file
img1 - crosshair for windowed mode
img2 - crosshair for fullscreen
That’s great! Congrats on getting what you need, and thanks for sharing it for others to use, as well 
