Convert qutebrowser's cookies to Netscape format

dump-cookies.sh

#!/bin/sh

{
    echo '# Netscape HTTP Cookie File' # needed by youtube-dl

    # There is no attempt to url encode $1, but SQLite already handles
    # characters like spaces, so only ? % and # should cause issues.
    sqlite3 -separator '	' "file:${1:-$HOME/.local/share/qutebrowser}/webengine/Cookies?nolock=1" "
SELECT
    host_key,
    IIF(host_key LIKE '.%', 'TRUE', 'FALSE'),
    path,
    IIF(is_secure, 'TRUE', 'FALSE'),
    IIF(expires_utc == 0, 0, expires_utc / 1000000 - 11644473600),
    name,
    value
FROM cookies;"
} > $XDG_RUNTIME_DIR/cookies.txt

# expires_utc is converted from the Windows NT Time Format to a UNIX timestamp

Also, could this be rendered as a qutebrowser userscript?

It should run fine as a userscript. You can even use $QUTE_DATA_DIR.