Is it possible?  I saw a post from 2017 that said there was a way to collect addresses etc, but wondered if any inroads had been made on this.

I had a brief look through the project upload section, but there's no option for physical items I can see there, closest would be physical games, but that's only for print & play it seems.

Would need itch to collect addresses & offer some way of either pre-filling postage costs, or working out postage costs.

If you haven’t already, you can find more info on it on Exclusive content & Rewards, it describes details of how to set up rewards, including to sell physical goods.

I haven’t used it before, so can’t say how much Itch does or you, and how much is for you to do, but I believe Itch expects you to handle delivery, and all the costs involved, which you should possibly include in the price to claim such a reward.