This would take a bit of work but you could do this with scripts and keybindings.
There is a tool called xdotool and it lets you simulate keyboard presses. You can bind your keyboard keys to run scripts that utilize this tool.
Using whatever language you prefer to pipe terminal commands, you can find specific process IDs with
ps aux | grep "process here"
xdotool search --pid "process ID here" you will get back multiple window IDs for a single application. I don't know how to sort through them to find the correct one, so what you could do is have your script, iterate thought the found IDs into
xdotool windowactivate "window ID here" which will bring up your window.
For example, my 1 key will be binded to run a script that find the process ID for "filezilla". Then it will find the window IDs with xdotool, take those IDs and then pass them through xdotool to pull up the window. The 2 key, could be "google-chrome"