Foot fungus?? Infection? Bumblefoot?

Are you sure that this is not dried droppings that have stuck to the toe?

I agree with Cody, it looks like a bit of droppings stuck onto his toe! He should preen it off or it will fall off naturally, so unless it seems like he's unable to get it off then don't worry

Thanks for reassuring me, several people I've showed the image to seemed to share this opinion! I will keep a close eye the next few days.

What is Bumblefoot (Pododermatitis)? Long recognized as a serious disease in raptors, bumblefoot, otherwise known as pododermatitis, also occurs frequently in psittacines. It is common in heavy-bodied birds such as Amazons and Hyacinth macaws, but is also seen in budgerigars and cockatiels.

https://hari.ca/avian-care/health-monitoring/symptoms-treatment-bumblefoot-parrots/#:~:text=What%20is%20Bumblefoot%20(Pododermatitis)%3F,seen%20in%20budgerigars%20and%20cockatiels.

P.S. Im NOT saying your bird has bumblefoot btw ... it does look like dried poop to me, but I'd be concerned because he hasn't cleaned himself. As Faery Bee has mentioned, popping his foot into some lukewarm water to soften and remove it is a good idea.

If you are unable to handle him if he isn't tame, I'd use a spray to wet it.

You really need to see underneath to make sure the skin is healthy. The poop staying there is not ideal, regardless of anything.

Good luck