That brings me to the question if pots are also needed for other emulators.
Maybe... if the emulator isn't super-resolutions aware (i.e. won't do horizontal scaling) then you'd have to use a standards mode and the modeline centering isn't as granular for those.
A while back I explored automating an Extron Rxi via serial port control. I managed to get an AutoHotkey script communicating with the Extron (e.g. query the current H and V position values, measured refresh rate and horizontal frequency, remotely set the H and V position, etc).
Idea would be to use AutoHotkey to monitor for changes in video mode and application focus then set the H and V positions accordingly.
I think this is entirely possible but I moved onto a more important project (using an Arduino controlled relay array to created a digital voltage divider that automatically sets the correct vertical size for each game in GroovyMAME).
For that last project, I have a working prototype (16 preset sizes only currently but could be expanded with more relays) but haven't had a time to write it up and share here (in the process of moving house).