Not sure if this is useful for anyone, but here is a version I have been
using without the RDE dependency.
(define-module (iwd-service)
#:export (iwd-configuration
iwd-configuration?
iwd-configuration-iwd
iwd-configuration-openresolv
iwd-configuration-coreutils
iwd-configuration-config-file
iwd-service-type)
#:use-module (gnu)
#:use-module (gnu services)
#:use-module (gnu system setuid)
#:use-module (gnu packages networking)
#:use-module (gnu packages dns)
#:use-module (gnu services admin)
#:use-module (gnu services dbus)
#:use-module (gnu services base)
#:use-module (gnu services shepherd)
#:use-module (gnu services configuration)
#:use-module (guix gexp)
#:use-module (guix records))
(define-record-type* <iwd-configuration>
iwd-configuration make-iwd-configuration
iwd-configuration?
(iwd iwd-configuration-iwd (default iwd))
(coreutils coreutils-configuration-coreutils (default coreutils))
(openresolv openresolv-configuration-openresolv (default openresolv))
(config-file iwd-configuration-config-file
(default (plain-file "iwd-main.conf"
(string-join
'("[General]"
"EnableNetworkConfiguration=true"
"[Network]"
"NameResolvingService=resolvconf")
"\n" 'suffix)))))
(define (iwd-shepherd-service config)
(match-record config <iwd-configuration> (iwd openresolv coreutils)
(let ((environment #~(list (string-append
"PATH=" (string-append #$openresolv "/sbin")
":" (string-append #$coreutils "/bin")))))
(list (shepherd-service
(documentation "Run Iwd")
(provision '(iwd networking))
(requirement '(user-processes dbus-system loopback))
(start #~(make-forkexec-constructor
(list (string-append #$iwd "/libexec/iwd"))
#:log-file "/var/log/iwd.log"
#:environment-variables #$environment))
(stop #~(make-kill-destructor)))))))
(define %iwd-log-rotation
(list (log-rotation (files '("/var/log/iwd.log")))))
(define (iwd-etc-service config)
(match-record config <iwd-configuration> (config-file)
`(("iwd/main.conf" ,config-file))))
(define iwd-service-type
(let ((add-iwd-package (compose list iwd-configuration-iwd)))
(service-type (name 'iwd)
(extensions
(list (service-extension shepherd-root-service-type
iwd-shepherd-service)
(service-extension dbus-root-service-type
add-iwd-package)
(service-extension profile-service-type
add-iwd-package)
(service-extension etc-service-type
iwd-etc-service)
(service-extension rottlog-service-type
(const %iwd-log-rotation))))
(default-value (iwd-configuration))
(description
"Run @url{https://iwd.wiki.kernel.org/,Iwd},
a network connection manager."))))
