Edit: This question was based on my misunderstanding of the NTP user guide linked below. The NTP utilities mentioned in the user guide are not compatible with OpenWrt's built-in BusyBox NTP daemon but instead requires that you switch to the full ntpd packages also mentioned in the guide. As you can see later in this discussion my needs were fulfilled by instead using OpenWrt's hotplug interface for my NTP needs.
root@OpenWrt:~# ntpd -h
ntpd: unrecognized option: h
BusyBox v1.31.1 () multi-call binary.
Usage: ntpd [-dnqNwl] [-I IFACE] [-S PROG] [-p PEER]...
-d Verbose (may be repeated)
-n Do not daemonize
-q Quit after clock is set
-N Run at high priority
-w Do not set time (only query peers), implies -n
-S PROG Run PROG after stepping time, stratum change, and every 11 min
-p PEER Obtain time from PEER (may be repeated)
-l Also run as server on port 123
-I IFACE Bind server to IFACE, implies -l
I don't see it...and doubt it, especially when the -h argument isn't programmed either.
If you want to see the NTP peer information and status via running software in the ISC NTP Utility Suite ntp-utils, then yes, you'd need to be running the accompanying ISC NTP Server Suite ndpd as well.
Ah right, thanks. I discovered it is sort of possible to check the BusyBox NTP setup by running its ntpd as a new process. You need ti get the settings from /etc/config/system and supply the -w flag to avoid fighting about setting time with the already running instance. This is what you get:
I understand now that BusyBox doesn't have any IPC or RPC interface to query the status of the running NTP daemon.
BUT the OpenWrt built-in configuration does have a hotplug interface for NTP: https://openwrt.org/docs/guide-user/base-system/hotplug
that provides an event-based API for me to get the information I need (basically getting to know when the router has been setup with synced time).
So the solution for me will be to keep the built-in NTP and add a script to /etc/hotplug.d/ntp.