"Remove photos" from phone, mac or both?

Dear Apple,

Could You try to be more specific, when You are going to delete my special memories?

Are You removing my photos from:

a) iPhone

b) Mac

c) both

d) Something completely different

I have offloaded my pics from my ipone and ipad to a certain folder for about 12 years now, just to keep then in "human controllable" archive, alongside the the hazarous maze called Photos.

I have not used iCloud Photos and neither will in the future.

I have used Photostream and just handpicked away ca. 7000 duplicates from 7000 pics (averaging one, but some had none and some had severals).

What I now would like to do, is wipe out all pics from both iDevices, which have those duplicates and then sync the "cleaned" folder from mac to them.

I suspect that both iDevices use apfs, so I'm not sure if this clears any space from them, but at least scrolling Photos will be much better experience.

Then some day, same spring-cleaning with mac's Photos.

First time I tried to check the new "Duplicates" function, the whole database corrupted.