I finally arrived at these three set-ups, with different specifications, depending on either minimal size or maximum light output duration. The next step should be a regulated charging module for hand/wheel cranks or a PV solar panel.
All three were tested for several weeks. The heat-sink can be smaller, as suggested in the BOM; I had no smaller one around when building the set-ups ; )
Maybe some fellow DIY home-lanternists may find them useful:
1. Minimal size and dimmable 366lm 3000K Ra 90+ 3,5h min. on full
2. Maximum light output duration and dimmable 505lm 3000K Ra 90+ 12h min. on full
3. Maximum light output duration but not dimmable 505lm 3000K Ra 90+ 12h min. on full