When Gnome session starts all application have in their environment variables
from /etc/profile (and ~/.profile). Sway doesn���������t. It would be awfully
convenient, if sway would do it as well. I cannot find anywhere in gdm/gnome
files where this configuration happens, but I have met even this trick
(https://tech.akom.net/archives/93-Getting-a-systemd-unit-to-read-your-.bashrc-file-for-its-environment.html)

    [Service]
    Type=simple
    User=some_user
    # Process the normal environment files for this user by starting a login
shell
    # and outputting it all in a temp file.  This makes it compatible
    # with the non-systemd init scripts that still rely on .bashrc
    ExecStartPre=/bin/bash --login -c 'env > /tmp/.magic-environment-file'
    ExecStart=SERVICE_COMMAND
    EnvironmentFile=-/tmp/.magic-environment-file