If it’s the intended behaviour of the picker to ignore the stored and shown date by instead showing the current date upon pending, I think that’s unnecessarily complex on ACF’s part.
If it’s a Zulu time format issue, then okay.
But I don’t think I have the wherewithal to make all these changes, I may just set it as a text field and will enter the time in the correct format manually myself.
Thanks for your ideas, as ever.