If we had another vessel to explore that option with then I'd rather use that, but I suspect BLubmuz may be right that the galley won't have time to do it. A test game indicating how long it would take to build a settler and worker would tell us whether the galley has enough time or not.
I had a quick try at this. Not only to see how long the Galley would have to explore, but to address the Worker or Settler first question. I'm not claiming this is optimal, but I'm using it as a starting point for discussions:
*We can get both a Worker and a Settler in Sirius by turn 62 if we build the Worker in Canopus.
*Due to health considerations we cannot chop in Sirius.
*I chopped both a WB and the Worker in Canopus (2 of the 3 PFHs) to speed production.
*The Galley drops off the Warriors in Andromeda on turn 52, and must return to Sirius by turn 62 to ferry Settler + Worker.
*Some choices were arbitrary (i.e. Granary after the Worker in Canopus, using the free worker turns to partially build a cottage in Sirius), and might have better alternatives.
43: Sailing complete start Alphabet
44: Warrior complete in Sirius, start Galley
45: No action, Gold mine complete in Canopus
46: Canopus grows to size 2, works FP and Gold
Worker moves 1N to PFH to chop.
47: Start chop
48: No action
49: WB finished in Canopus, moves to Fish, start 2nd WB
Chop finished
50: Sirius grows to size 6 works 2 scientists + 2 Fish + 2 Gold
Galley finished in Sirius, start Settler
2 Warriors + Galley move to Andromeda
WB in Canopus improves Fish, Canopus works Fish + Gold
Worker moves 1NE to chop
51: Alphabet complete start Math/IW/Aesthetics? (Math in this example)
WB done in Canopus moves to 2nd Fish
Start chop in Canopus
52: WB improves 2nd Fish in Canopus, Canopus continues working Fish + Gold
Galley arrives at Andromeda, unloads Warriors, free to move.
53: chop finished in Canopus
54: LP free to start new action
55: No action
56: Worker2 finished in Canopus, starts Granary, Worker2 moves to 1W of Sirius
57: Mathematics done, start next tech
58: Worker2 arrives 1W of Sirius
59: Worker2 starts Cottage
60: No action
61: Canopus grows to size 3, works 2 Fish + Gold
Cancel Cottage build in Sirius (2 turns left)
62: Settler done in Sirius, boards Galley, Worker2 moves to Sirius boards Galley