That hope has not been justified... My Z3 Play was dead this morning after the charging level still had been at 70% when I went to bed last night. Quick-Charged back from what seemed to be zero to 100% within a few minutes, it booted up, but dropped dead again shortly after disconnecting, only showing the charging symbol again.
Now, with my mixed experience with the local repair shops around here, it very much looks like I need to buy a second substitute phone to bridge the time between my first-ever non-keyboard phone (the original Moto Z that I bought in early 2019, for the Livermorium