Hello @4LT, this reads as a feature request for the Steam client instead of Proton itself, so I've transferred this issue to https://github.com/ValveSoftware/steam-for-linux/issues/5766.
Winetricks is your friend, in Winetricks & the prefix of your choice, run task manager & use that to start up any application you want in that prefix, from anywhere on your hard drive.
Feature Request
I confirm:
contain this feature already.
Description
I'm requesting an easier means of running utilities under Proton. I think a good solution would be to have Steam auto-detect the file type of programs added through 'Add a non-Steam game' and run them under proton if they are Windows executables.
Justification
Some games provide utilities that need wine/proton to run, such as Worms Armageddon's sound bank editor. Currently, the only way to get at them (that I know of) is to take an existing steam game and set its launch options to something like
/path/to/proton waitforexitandrun /path/to/utility && echo %command% >/dev/null. This is cumbersome, and requires swapping launch options every time you want to switch between the game and the utility. Additionally, trying to run Proton as a non-steam game does not work because it does not run under the same environment as it does when run from a steam game's launcher.Risks