I think a lot of Kickstarters have physical rewards because they’re cheap and mass producible. For any amount of pledges, just order that amount from some crafting company and they make it for you. Digital rewards outside of soundtracks and Beta testing usually involve pledgers getting something inserted into the game, which takes extra work per pledge. You would be forced to put limits on how much each pledge can be taken. You could maybe make a little character creator and have people create their own NPC (or perhaps special humanoid enemy that varies in appearance) for you, but even that takes time to put each one in.

All the same, I agree with the redditors that physical rewards aren’t that great for solo developers. You would need to figure out shipping everything or hire someone to do it for you, both of which hampers the money you would receive from making those pledges. You might have to lower the pledge goal, but it’ll save you a lot of headache. Personally, my house has too much junk as it is; some collectible pin or poster wouldn’t excite me at all.