Update, Oct 24: Following up on this thread. Headed In 0.4.0 (build 25) has been Waiting for Review since Oct 18, and an expedite was granted today. Separately, our study app Hall Pass 1.0 was rejected under 4.3 / 4.2.6 on Oct 19. We replied in App Store Connect the same evening with answers to all nine questions (it replaces three earlier study apps we folded into it) and have not heard back in five days. If anyone from App Review sees this, a look at the Hall Pass reply would be appreciated. Thanks.

Update, Oct 14: Headed Back 0.1.0 was approved on the evening of Oct 13, about ten days after the Guideline 2.1 reply, so that one is resolved. Headed In 0.3.0 (6817955207) and the three study apps are still Waiting for Review. Leaving this here in case it helps anyone else gauge the wait after a 2.1 questionnaire on a new account.