How to access imported photos on iPhone

Hi!

A few months ago I decided I wanted all my photos to be on my iPhone and not on my Mac. I went ahead and imported (manually) through sync (not iCloud) from Mac to iPhone over 5000 photos without any problems. At a later time I formatted my Mac because of another issue unrelated to this one. Now I am trying to export my photos that I had imported that time, but I don´t have any permissions at all to move/copy/transfer them.

What does this mean? Are they locked in my iPhone forever? Do I really need to shell out 50 dollars for a third party app to extract them? Surely there must be a better way to solve this. This are MY photos, I took them, I own them, why can´t I then edit them?

Disclaimer to avoid unhelpful advice:

• I don't use iCloud, never have and it is not on anywhere (Mac/iPhone).
• I tried importing through photos, but the app only recognizes recent pictures, not the folder called "my Mac" that has my imported images.
• I tried importing through "image transfer", same result as photos app.
• I tried airdropping, nothing happened.
• I tried transferring to a cloud app (one drive/google drive etc) nothing worked, did not recognize the 5000 photos, only the recent ones.

So clearly the photos are stuck on my iPhone in some sort of limbo. I can look at them, they show up in memories and "all photos", but they are not in my camera roll, but in a separate folder called "my Mac".