Thanks for playing and glad you enjoyed!
For the way it launches, that's a workaround for Itch's setup that otherwise blocks saving games to local storage in some browsers (Safari, especially). It does open in a new tab though by default, so you should be able to get back to the game page tab easily. Details here if you're curious about the technical reasons and alternatives :).
There is an end of game scene - after you do the final heist, and optionally say goodbye to your reticent friend, just walk out the south exit of town. It's just a single dialog of text though and a "congrats, you win". Since the game saves your progress (in all browsers ;), you can go back and see that if you missed it. It's definitely a little easy to miss though, I think, making that more clear would be a good thing to change.