As of November 2024 for snapshots from the main development branch and future stable release builds (possibly also including the upcoming 24.10 series), the package manager in OpenWrt has changed from opkg to apk.
This new package manager offers a number of advantages over the older opkg system and is a significant milestone in the development of the OpenWrt platform. The older opkg package manager has been deprecated and is no longer part of OpenWrt.
As this represents a fundamental shift in the method for installing and managing packages, there is an active discussion in the Talk about Documentation subsection of the forum, including the options and syntax used by this new system.
Note: This change does not affect 23.05.
(And as of 15 Nov 2024, also the 24.10 branch is still using opkg.)