I found a working solution for the problem people had with 1password on Mac when using multiple profiles. Here the problem was that the 1password extension reported “code signature could not be verified” when filling out forms.
The whole thing works when using the Mac-way of opening apps, for example:
open -n -a Firefox --args -P Work
will open the profile called "Work". As we use the parameter -n, we can launch several instances of this application.