Two items for dev-review:

* https://github.com/zephyrproject-rtos/zephyr/pull/26025#issuecomment-656044858 against https://github.com/zephyrproject-rtos/zephyr/pull/26750#discussion_r452120857 and the question of whether optional API should be declared or not relative to use of `if (IS_ENABLED())`.  This may also be appropriate for API.

* https://github.com/zephyrproject-rtos/zephyr/pull/24794#pullrequestreview-444964843