@Krakatoa If you are interested, I got other systems working too
PS1 games:
SSH into \home\RetroPie-Setup\scriptmodules\libretrocores\
Find lr-pcsx-rearmed.sh
Open it with Notepad ++
Change the section to be like this:
function sources_lr-pcsx-rearmed() {gitPullOrClone "$md_build" github.com/SindenLightgun/pcsx_rearmed.git}
Now go into EmulationStation, or SSH into your box (sudo /home/pi/RetroPie-Setup/retropie_setup.sh)
Go into Options>RPSETUP
Manage packages>Manage main packages>lr-pcsx-rearmed>Remove
Then do an update from source.
Now when you launch PS1 games, go into Quick Menu, then in Options select Pad 1 Type = guncon
When that has finished then you load lr-pcsx-rearmed as your emulator as usual. Then on the menu under options you can change Pad 1 Type to "guncon".
Tested on Elemental Gearbolt, Time Crisis I and II and it works well. However, some games are not working, Die Hard/Die Hard 2, Lethal Enforcers I and II.
For NES,
got into Retroarch Quick Menu
Change Port 1 binds device type to "Zapper"
Map Wiimote buttons same as on Dreamcast example
In Quick Menu, enable "lightgun settings"
then go to Options and change Zapper Mode to "Touchscreen"
save configs and restart
For SNES, similar to NES, but when launching a game, when the splashscreen for NES comes up, press the button on your controller to bring up the launch menu
Change the emulator for the rom to "lr-SNES9x"
When Retroarch loads, go to main menu inputs
Go to Port 2 Binds
Select SuperScope
Map trigger, alt fire like before
In Quick Menu, check lightgun mode "touchscreen"
Master System, same as NES
Port 1 - MS Light Phasrer
In Quick menu turn on show cross hair
touchscreen mode
save game mappings
Megadrive/Genesis:
Set port 2 binds to "MD Menacer"
Same settings elsewhere (i.e. touchscreen)
Still not bad progress!