My tools for macOS

Safari_ReadingList_to_csv.py

Exports DateAdded, DateLastViewed (read or not), URL and Title for all links in ReadingList.

Usage

For macOS Big Sur you need to allow Full Disk Access for yout Terminal:

System Preferences → Security & Privacy → Privacy → Full Disk Access → Terminal (tick ☑️ it).

Restart Terminal.

Command ot Export:

python3 Safari_ReadingList_to_csv.py

Generates:

readinglist.csv

in current folder.