Yes - seconding the thanks for all the details offered on your use case - thank you!
It sounds like you’ve considered different security scenarios in regards to having CHWs log out regularly, but we otherwise strongly recommend PINs required to unlock the phone as well as full disk encryption to protect sensitive CHT data in case a device is lost.
Also - in the scenario of a device being swapped between CHWs, are you aware of CHW Offline Replace feature? This feature allows a Supervisor take a phone from a departing CHW, enter a PIN on a special form in the CHT and give it to a new incoming CHW - all with out any connectivity.
After the form is submitted, a new CHW can immediately begin using the phone to service patients in that same area, again with no connectivity needed. At a later date, when the new CHW has connectivity, they can sync the data created while offline, receive a token login link and proceed to use the phone with their newly created account, an entirely automated self serve process after the initial supervisor PIN is entered.
You can read the docs and see this forum post with a demo video to find out more!